Yet Another Cycling Forum
Random Musings => Gallery => Phototalk => Topic started by: andyoxon on 30 October, 2008, 01:29:11 pm
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"Why Digital is Dying"
http://www.kenrockwell.com/tech/00-new-today.htm
It's been turned into an 'article'...Why We Love Film (http://www.kenrockwell.com/tech/why-we-love-film.htm)
What do you think? I took a roll of 35mm Fujichrome Provia, this August and still haven't had it developed - mainly because I want to find the best value scanning service; but it did feel good. Does KR have a point..?
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Most of his arguments even if they are valid only really apply to pro users / very serious armatures and ones doing art house photography anyway. For the millions of happy holiday snappers out there digital is millions of times more convenient than film and much cheaper.
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He does make some interesting comments, I am a die hard filmie and spent many a happy hour on plate camera's at college and shoot loads of 120 B+W. Digital wont die, the corporates have too much money in it, and as pcolbeck points out the average camera user is now on digital.
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Isn't he known for blogging controversial things.
Maybe even to get his hit rate up?
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A lot of what he says is nonsense with negative spin on positive benefits of Digital. I assume it's tongue in cheek.
No attention wasted looking at the back of the camera after each shot.
Well, the fact you can pull up an exposure histogram of your shot immediately could be seen as quite an advantage. Checking for sharpness another.
No computer required, ever! Pros use light tables many feet wide. You can't get computer monitors that big for sorting and selecting.
So having a huge light table suddenly becomes more convenient for the process than a PC?
No motel shenanigans. You have no digital garbage to take out, like downloading, filing, cataloging, sorting, organizing, posting, or organizing.
He means he doesn't have the option to do any organising
No friggin' shooting delays.
He may have a point here. Some digital cameras do have an LCD/exposure/focus delay but the high-end cameras don't suffer from this any more.
Film costs much less
The most stupid claim because he argues that you shoot less film as the format gets bigger. That's because it costs so much not because you get to be a better photographer with bigger film. His entire reason behind shooting less film is really down to the cost of film.
Being able to shoot many shots of the same subject (at slightly different settings) is a huge bonus for the amateur who can't afford to motor-drive their way through film like the pros. (Patrick Litchfield was stopped at immigration on some Sun-kissed paradise becasue they thought he was illegally importing film. He had to convince them that he was going to use them all (hundreds of rolls) for 12 Pirelli calendar photos)
Of course film can't be touched for some things (resolution, dynamic range Pirelli calendars for example) but the list isn't as long as he would have us believe.
Tongue in cheek.
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While I think its nonsense to argue that digital is dying, there's no overall financial saving to digital for the typical enthusiast because you spend all the money that you would have spent on film on more and better cameras, lenses and accessories. What is very nice, though, is not having a defined cost per frame - it feels like it's free when you're taking a picture, and of course you can take more pictures alogether.
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Meh, scroll down, the whole blog is an anti-digital polemic.
I know this about digital: I can now afford to take all the photos I want to take. The rest is detail.
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Just a snappy title.
Everyone else is saying "Film is dying", these are reasons why it's not. It's almost dead, but will not disappear completely for many of the reasons given. A few are a bit silly though.
A pro I spoke to ages ago said she preferred to take film on a job, with digital she ended up with so many shots it took ages to sort them out, which was more expensive in time than the cost of film.
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Archiving is the main problem. I've got a couple of biscuit tins with all the 8mm movie my family ever took. Very pricey per minute, but 45 years later I can see us in the early 1960s. The same is true of slides and B&W prints. You've doubtless got a biscuit tin or two in your family. I'm unsure of the longevity of digital formats, optical or hard drive. Video tapes are the worst, print-through degrades them fairly quickly. My mate Dave digitised a load of his best photos recently, he started off doing a few landscapes but soon realised that it was people that mattered. The danger is that all those precious people shots end up in the middle of a whole load of generic sunsets on a DVD or Hard Drive. My Grandad did some editing of his home movies and it's now the stuff he cut out that gets the most response.
Damon.
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Digital looks crap.
There, that's my considered view.
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You can print with 'archival' quality inks if prints are your thing and, in theory, digital images are lossless if you backup correctly. It's easier in some respects to ensure the integrity of digital images as it's so easy to store copies 'off-site'.
I lost a load of rather (sentimentally) valuable cine film in a leaking roof incident several years back. Single point of failure in my backup plan (Cardboard box in the loft).
Trusting a single £50 hard-drive with all your images is asking for a similar disaster of course.
PC Hard-drive, external hard-drive and off-site storage (that's my Mum's House to you) of regular DVD backups would be my choice for 'valuable' images. If I was a pro-photographer then I'd also use the services of a reputable data-storage company.
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You're more likely to print up generic sunsets than the funny shots of the kids. I've already lost track of stuff I took on digital five years ago, I can see the biscuit tins from here. Ultimately the DVDs wil be easier for our heirs to throw away, actual pictures are harder. I worked at a waste transfer station once, and it was quite upsetting seeing interesting photo albums dumped, it'll be a lot less upsetting with shiny plastic discs.
Damon.
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you're more likely to print up generic sunsets than the funny shots of the kids.
I'm not sure about that. The only pictures that I actually print nowadays are of friends and family and they go into 6x4 albums like my old film prints did.
chillmoister has exhibited large prints from digital photos and they look stunning. I think it's getting harder to tell the source of prints now. Transparencies projected onto a large screen however are a different league entirely. I sometimes miss my Kodachrome 25, projector and my parents' 25 foot living room and white walls.
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Ooooh! Kodachrome 25. Now that was a film.
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I found it a bit blue, and the speed to be a little optimistic.
What was sad about digital was that some really major advances were being made with film in the last ten years before it became a niche. It wasn't a technology that had run its course, and had the advantage that upgrading your old camera to the latest technology just involved buying a roll of the new film. Upgrading your digital camera usually involves dumping it and buying a whole new one.
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Well I know that the pictures I now take on digital look much better than the ones I used to take on film. And that is mainly because my photography has improved due to the ability to take lots of pictures, and to get same day feedback.
Regarding the "digital looks crap" statement, I would really like to see a specific example (taken on a half decent dslr*), together with an explanation of why it looks crap. To my eye a carefully shot digital looks as good (on average) as a carefully shot film.
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I am a die hard filmie and spent many a happy hour on plate camera's at college ...
So did I. But I'm fairly sure I've moved on now ...
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Archiving is the main problem. I've got a couple of biscuit tins with all the 8mm movie my family ever took. Very pricey per minute, but 45 years later I can see us in the early 1960s. The same is true of slides and B&W prints. You've doubtless got a biscuit tin or two in your family. I'm unsure of the longevity of digital formats, optical or hard drive. Video tapes are the worst, print-through degrades them fairly quickly. My mate Dave digitised a load of his best photos recently, he started off doing a few landscapes but soon realised that it was people that mattered. The danger is that all those precious people shots end up in the middle of a whole load of generic sunsets on a DVD or Hard Drive. My Grandad did some editing of his home movies and it's now the stuff he cut out that gets the most response.
Damon.
This is false.
Please take your ageing analogue images and make backup copies of them all! ;D
Then report back on how long it took to copy your analogue images and how you did it (and maybe whether you used digital in the process of copying ;) ) and whether the copy that you made was identical to the original. Oh, and please give the same answer for the digital images. ;D
I have bucket loads of shafted images taken analoglly. Why? We had a flood. I had no copies. All beyond repair.
Copying them would have taken me, well, how long it would have taken to copy the contents of 5 Patterson 35mm negative albums stuffed to the gills? :'(
Edited for YACF Goggles
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Watch the repeat of Five's Gadget Show (on Sunday?) to see film compared to digital. They massively blew up shots taken on 35mm film and "full-frame" digital (with similar cameras & same lens by professional photographer) and hung them on a multi-storey building to compare. They all thought the digital one was superior in a number of ways.
I don't know how good a test it was, but at least it questions the assumption that digital photographs are still not as good as film ones.
[EDIT: Not "same camera", of course]
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Ken Rockwell also insists that there's no point in shooting RAW and that jpegs are just as good.
I think he mainly does to generate hit counts.
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I don't know how good a test it was, but at least it questions the assumption that digital photographs are still not as good as film ones.
Not a particularly good test in many ways, but as you say it shows you can't just say one is "better" than the other. For most people, the quality of either nowadays is way higher than "acceptable", so it comes down to convenience and cost. Once you start becoming super-critical, you have to choose what you want out of the image and choose your equipment and media accordingly.
Ooooh! Kodachrome 25. Now that was a film.
My all-time fave was Technical Pan, sadly discontinued many years ago. :'(
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Ken Rockwell also insists that there's no point in shooting RAW and that jpegs are just as good.
I think he mainly does to generate hit counts.
Many years ago (before digital cameras) a mate of mine did his PhD on jpegs and other compression techniques. One of the findings was that lightly compressed jpeg images were almost universally regarded as higher quality than the uncompressed version.
That's not to say there's no advantage shooting raw and enhancing out of camera, but does throw some light on Rockwell's opinion.
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I found it a bit blue, and the speed to be a little optimistic.
Yes and yes (and very contrasty) but, using a tripod, it could capture incredible levels of detail (our living room wall was about 15x8feet letting you see the fleas on the back of fleas on a fly) I wonder what the equivalent megapixel rating would be.
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I found it a bit blue, and the speed to be a little optimistic.
Yes and yes (and very contrasty) but, using a tripod, it could capture incredible levels of detail (our living room wall was about 15x8feet letting you see the fleas on the back of fleas on a fly) I wonder what the equivalent megapixel rating would be.
This only really applies if you're buying top of the range lenses though. In the vast majority of cases resolution will be limited by the optical performance of the lens rather than the detector (be that digital or film). I only have one lens (300mm f4 Nikon) which you can just about see pixilation on 6MP digital camera - and even then you have to look hard. That might get some benefit from using film rather than digital, but I wouldn't notice the difference with any other lenses I have. Of course, if you are going to the bother of slide film and projectors, you probably ARE using lenses which justify it :)
To answer the question though, low ISO films have grains about 0.3um apparently (according to a quick googling). So, for a 35mm format (36x24) the equivalent MP would be 9600MP...
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However, the grains are not uniform in size or distribution, so I wouldn't have thought there is a direct comparison between size of grain and size of pixel. You'd need a fair few grains to mimic a pixel.
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The main problem with digital is that pixellation is unattractive, whereas grain looks more natural; your eyesight is also grainy (just look at a plain wall). Too many digital images look like still video.
The new Canon EOS 1Ds has probably got there in terms of resolution - you can make a 30" x 20" print from it - but it's not exactly mainstream technology.
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I only have one lens (300mm f4 Nikon) which you can just about see pixilation on 6MP digital camera - and even then you have to look hard. That might get some benefit from using film rather than digital, but I wouldn't notice the difference with any other lenses I have. Of course, if you are going to the bother of slide film and projectors, you probably ARE using lenses which justify it :)
I think what I wrote might be bollox... forgot about all the bayer resampling. Not sure how that affects the output image, but it suspect it means you see less pixilation than you'd expect from a simple optics argument... Would need to look at the individual channels in a raw frame (which I don't take because I shoot sports and raw is way to slow and fiddly for that!)
From an optics point of view, film does theoretically offer a big resolution advantage. Diffraction limit for 24mm f/2.8 lens is 1.6 microns (well sampled by a slow film; very poorly sampled by a typical digital detector)...
Right, going to have to borrow a Nikon film body now...
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To be honest - I've never seen pixellation under normal (printed) viewing conditions. I even have some pictures on the wall taken with my first (2mp) camera at around 9x7 size. Hang on - I'll go have a look. No, no obvious pixellation. It is not the sharpest print in the world (what do you expect from 2mp), but perfectly acceptable to hang on the wall.
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Just for interest - a look at what can be achieved with only 3MP
Untitled Document (http://www.nyphotographics.com/blowupsample.htm)
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I have a 1.2MP image printed at 9" x 7".
It isn't 'sharp', and I notice chromatic aberration but you need good eyes or to get close to see that it is effectively over enlarged. I notice this, non-photographers don't.
What matters is the content.
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The Gadget Show just did a test of a high-end 35mm film vs digital, using the same lens and blowing the image up to the size of a whole office block. Digital spanked film.
This is one of those holy wars like linux/windows or cake/pie.
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The main problem with digital is that pixellation is unattractive, whereas grain looks more natural; your eyesight is also grainy (just look at a plain wall). Too many digital images look like still video.
The new Canon EOS 1Ds has probably got there in terms of resolution - you can make a 30" x 20" print from it - but it's not exactly mainstream technology.
I'm not too sure about pixellation problems. I have an example 12Mp image from a Canon G9 and I zoomed until it pixellated. At that zoom level the image would be nearly 2 metres wide. The optimum wiewing distance for an image that big would disguise much/all of that pixellation of course (I could see pixellation when viewing it sat at my desk at arm's length).
Zoomed to 1 metre across there really isn't any pixellation visible, even when I get really close to the screen. 12Mp is fairly mainstream now and 36" wide prints are fairly specialist
My 7Mp Canon's images starts to pixellate at around 56" wide (sorry for mixing metric and imperial) but we're talking about a 'grain' effect rather than noticeable square pixels.
www.dpreview.com (http://www.dpreview.com) allows you to download samples from the cameras tested. The lastest 12Mp and above models have pretty spectacular resolution (especially when you consider what's happening down at semicondictor level).
It's very easy to zoom into a digital image and spot pixellation (5 clicks does it on mine) but forget just how big that image would be if you could see the whole thing.
Note. Almost all the images I post on YACF are 640x480 which is only noticeably 'un-pixellated' at 6x4 postcard type enlargement.
Most people don't have the ability to print bigger than A4 and once you commit an image to paper you lose a huge amount of dynamic range so the gap between a projected film Transparency (as good as it gets?) and a Digital image displayed on a quality monitor narrows significantly.
I wouldn't like to bet my own money on being able to tell an A4 print from film and one from a 12Mp Digicam.
I'm now curious to see if DPREVIEW have got any images from 20Mp sensors
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The main problem with digital is that pixellation is unattractive, whereas grain looks more natural; your eyesight is also grainy (just look at a plain wall). Too many digital images look like still video.
I you like film grain, you can add a film-like grain effect to your digital images! Pixellation is not normally visible because the pixels are so small.
Excessive noise and over-processing* makes many digital images look unattractive or unnatural - but you would be hard pushed to tell the difference between digital and film with good low noise/small grain examples of both.
* Including over-sharpening, excessive noise reduction, unnatural brightness/contrast levels - done by the camera or post-processing. You can do better with a better camera or more subtle processing.
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The Gadget Show just did a test of a high-end 35mm film vs digital, using the same lens and blowing the image up to the size of a whole office block. Digital spanked film.
This is one of those holy wars like linux/windows or cake/pie.
From the quality of gadget show tests I have seen - I am more inclined to believe the exact opposite of whatever the gadget show concludes.
;D
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Agreed, the gadget Show almost always tests aspects of an item that seem irrelevant, downright stupid or are blatantly unscientific.
In honour of the Gadget Show here is my unscientific and meaningless test.
It's a download of a 15Mp image and a crop from that image to show the amount of pixellation.
Original image (downsized to 640x480 by Photobucket)
(http://i170.photobucket.com/albums/u249/freddered/Various/15Mpcanona.jpg?t=1225548965)
Now a crop from the (original 15Mp) Image
(http://i170.photobucket.com/albums/u249/freddered/Various/15mpcrop.jpg?t=1225550590)
It's pixellated to buggery but the original image would be 11 feet across at that level of zoom, you'd be viewing the image at several metres distance and so wouldn't notice much/any pixallation.
Edit. Actually, looking at it again now it's posted, it shows just how far sensors have come in the last few years. You could actually get a (admittedly poor) 6x4 print of the girl for a family album if you were desperate.
You can play "Where's Wally?" using the original image
Or, "Where's Brommie?"
(http://i170.photobucket.com/albums/u249/freddered/Various/15Mpbrommie.jpg?t=1225551491)
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And a response from film.
This picture here:
(http://www.compbio.dundee.ac.uk/~dmamartin/lf/nv_t.png)
Look at the white dot on the riverside about 50 pixels in from the left hand side.. This is it expanded:
(http://www.compbio.dundee.ac.uk/~dmamartin/lf/t_z_t.png)
You *can* print this 6 feet wide and it still looks sharp at close examination.
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Impressive stuff, but I don't think anyone is arguing that you don't get more grain per inch than pixels, just that it takes more and more extreme examples to reveal the difference with modern sensors. (Nice photo and lens by the way David)
For a regular "Family Album Snap" I think that 640x480 is juuuust about acceptable for most people assuming no cropping is required (see London scene above).
The race for more and more pixels has become crazy though. 99% of people will never print larger than 6x4" and yet they will disregard 7Mp cameras in favour of 12Mp cameras at 3x the price. My next purchase may be 12Mp (but because I want the feature set of a specific camera rather than actually wanting 12Mp per se).
For the regular Joe in the street I'd say get a bargain, end-of-line, 5Mp or 7Mp camera from one of the big names (Canon, Nikon, Olympus, Pentax and so on) and they'd be more than happy with the results. "Highly Recommended" from DPREVIEW is one of the more meaningful awards around.
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For a regular "Family Album Snap" I think that 640x480 is juuuust about acceptable for most people assuming no cropping is required (see London scene above).
The race for more and more pixels has become crazy though. 99% of people will never print larger than 6x4" and yet they will disregard 7Mp cameras in favour of 12Mp cameras at 3x the price.
But it's always nice to have the option of cropping and being able to print big. I'd hate to take the perfect shot and never have the option of having a copy of it bigger than A4.
To me, the only drawback of digital is the limitations in size. A 10mp image will never be bigger than 10mp. With film you can scan to whatever size you need. For enlargements at ultimate clarity, film and a quality scan will kick digitals arse every time so I'm sceptical of the Gadget Show test.
Even a pro 30mp camera can only produce an image of about 570mm x 370mm at 300dpi print size which if you are doing posters at A2 or A1, is less than ideal. Obviously home users don't need to worry about these sorts of sizes and resolutions but you can see why some pros still haven't fully embraced digital.
There are places that can offer drum scans at 12000dpi so even 35mm works out at 179mp equivalent and 6x6 medium format a whopping 803mp. The best digital can manage at the moment is about 60mp (http://www.phaseone.com/Content/p1digitalbacks/P65plus/Introduction.aspx) and at £20,000 for the back and another £20,000 for the body it's not something even most pros can afford.
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Even a pro 30mp camera can only produce an image of about 570mm x 370mm at 300dpi print size which if you are doing posters at A2 or A1, is less than ideal. Obviously home users don't need to worry about these sorts of sizes and resolutions but you can see why some pros still haven't fully embraced digital.
There are places that can offer drum scans at 12000dpi so even 35mm works out at 179mp equivalent and 6x6 medium format a whopping 803mp.
Care to guess what the film I showed above was scanned at? It is Velvia 50 and you can see the grain in the scans. With digital (and film for that matter) you can use an appropriate upresing algorithm to get a pleasing to the eye shot. Once your resolution is better than that of the grain of the film then you are onto a winner with digital.
..d
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12MP in one camera isn't 12MP in another, quality-wise.
Size of sensor is critical.
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Even a pro 30mp camera can only produce an image of about 570mm x 370mm at 300dpi print size which if you are doing posters at A2 or A1, is less than ideal. Obviously home users don't need to worry about these sorts of sizes and resolutions but you can see why some pros still haven't fully embraced digital.
There are places that can offer drum scans at 12000dpi so even 35mm works out at 179mp equivalent and 6x6 medium format a whopping 803mp.
Care to guess what the film I showed above was scanned at? It is Velvia 50 and you can see the grain in the scans. With digital (and film for that matter) you can use an appropriate upresing algorithm to get a pleasing to the eye shot. Once your resolution is better than that of the grain of the film then you are onto a winner with digital.
..d
4800dpi? I remember that shot from the Holga discussion. It's a beauty.
I don't mind film grain (at least it looks natural unlike digital noise) so I still prefer to scan film for those occassions when big images are required. I think my mate Anna (http://www.annaisolacrolla.co.uk/index.html) agrees, as although she's just spent a small fortune on a Hasselblad digital will still use 6x6 film when the big stuff is needed.
Jaded is right though. The only thing a larger megapixel camera will result in is a larger image. Quality comes from the sensor and the lenses and if you don't have quality, what's the point.
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4800dpi? I remember that shot from the Holga discussion. It's a beauty.
2400 I think. My feeling is that I havemore of a problem with diffraction on that image than film grain. Focussing was non-trivial - the cheat is that it was a 5x4 camera, not 35mm.
I don't mind film grain (at least it looks natural unlike digital noise) so I still prefer to scan film for those occassions when big images are required.
Digital noise is nothing to do with resolution. It is to do with exposure. Take a badly exposed film and process it badly -- the grain will look terrible.
I also think your natural/unnatural is based on what you have grown up with.
Jaded is right though. The only thing a larger megapixel camera will result in is a larger image. Quality comes from the sensor and the lenses and if you don't have quality, what's the point.
Absolutely. I won't buy compact cameras with silly numbers of pixels. 5 mp is more than enough. Using them properly is even better.
..d
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Even a pro 30mp camera can only produce an image of about 570mm x 370mm at 300dpi print size which if you are doing posters at A2 or A1, is less than ideal. Obviously home users don't need to worry about these sorts of sizes and resolutions but you can see why some pros still haven't fully embraced digital.
You can always resample an image to a larger size. You won't get any more resolution of course, but you can make a digital image as large as you want...
A digital image direct from the camera is exactly the same as a digital scan of a film. A 12MP full frame digital sensor will produce the same resolution as a 3000dpi scan of 35mm film...**
So, in fact, the image David showed (which is beautiful. I've always loved that view of Dundee -- especially in a rear view mirror ;) ) should be equivalent to a 12MP digital image.
Or have I got myself confused? (suffering from lack of oxygen at 14000ft at the minute, so may well have!)
edit: yes I have. Didn't pick up was 5x4 film! That is a bit of an unfair comparison though -- a 5x4 image is going to have higher resolution than a 35mm film image too...
** probably not quite, as I imagine negative scans don't do bayer sampling to get their colour info -- anyone know?
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I've been totting up how many prints of digital photos I've done, then it occurred to me that the main hard copy archival source I have for my decent cycling photos is Arrivee. I don't think I would ever have bothered submitting negs, slides or prints. That's where digital has been liberating, in creating a mechanism whereby ordinary people can share their good images. Technical quality is a bit of a red herring here. The best photos are composition led, the best aid to that is location scouting and continuous shooting. For the two Arrivee covers I have had, I rode both 200km events specifically to take the shots which appeared. Digital enabled me to compose the shot prior to the arrival of the main subject, then to check the results so that I would know if I needed to take more.
But on PBP 2007 we took 5 hours of video and a large number of digital stills. The one picture we have up is a poor quality Polaroid taken with my Grandfather's camera, it shows me, Heather, M Series, Mike Thompson and Riccardo Gravina before the ride. Being a Polaroid the actual picture was there with us 90 seconds later and is a unique record, a single artefact unlike the rest of the stuff. Everything else is work, that's a memento.
(http://farm3.static.flickr.com/2334/2541662554_e2ac10f119.jpg?v=0)
Damon.
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Quality comes from the sensor and the lenses and if you don't have quality, what's the point.
But I agree with Really -
Technical quality is a bit of a red herring here.
There are loads of good reasons for taking photos that have little to do with 'quality'.
My observation is that most people take photos just because they enjoy it (look at the picture of Really, above, to see what I mean) - and quite frankly in the case of film, if the camera wasn't even loaded it would make naff-all difference. So what price quality then?
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But wouldn't it eat away at your soul if you'd taken the photo of a lifetime on a 3MP camera? You could never hang it on your wall.
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But wouldn't it eat away at your soul if you'd taken the photo of a lifetime on a 3MP camera? You could never hang it on your wall.
You could hang it on a wall or at least put it on the mantlepiece/bookshelf.
What would eat my soul would be if I'd not taken the picture at all, not the size I could get by enlargement.
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But wouldn't it eat away at your soul if you'd taken the photo of a lifetime on a 3MP camera? You could never hang it on your wall.
Yes you could. People hang Monet paintings on their wall. They just don't stand too close to them to view, so they see the whole image rather than the individual blobs of paint. Same thing with posters of photos taken on high ISO film. Looks too grainy when you look close-up, but OK when standing back.
If you want more detail, you don't have to use film, just higher resolution digital.
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All of my views are coming from a print background (so not particularly important to most users). I totally agree that the most important thing is the ease of use, the fact this allows far more opportunities for pictures of loved ones and the interest in photography in general that digital has allowed. I would never argue against that and I'd absolutely love one myself.
You can always resample an image to a larger size. You won't get any more resolution of course, but you can make a digital image as large as you want...
A digital image direct from the camera is exactly the same as a digital scan of a film. A 12MP full frame digital sensor will produce the same resolution as a 3000dpi scan of 35mm film...
But the point is that 12mp image will only ever be 12mp. That 35mm film can be scanned at anything up to 12000dpi (or 180mp). Resampling digital images for print is only possible to a certain extent, you can't just make a digital image as big as you like unless it's only ever going to be viewed on a screen or printed at low res. That's one of the drawbacks as a lot of people think because it's digital you can do pretty much anything with it. I'm sent tiny 800k images all the time and am expected to use it in a magazine at A3. Clients see it large on their computer screens and can't understand how it can't be printed at the same size.
For instance if I'm sent a 72dpi jpg that's 36cmx23cm and I convert that to 300dpi for printing it's physical size is reduced to 8cmx5cm and can't be printed any bigger. To make it bigger the resampling programme has to make a 'best guess' and add pixels where none exist which always effects quality and the bigger you need to make it the worse it gets.
Digital noise is nothing to do with resolution. It is to do with exposure. Take a badly exposed film and process it badly -- the grain will look terrible.
I also think your natural/unnatural is based on what you have grown up with.
Absolutely. But people working with film are much more likely to expose properly in the first place. And maybe it is what I've been used to growing up, but to me a grainy black and white shot with some 3200 film looks moody. A similar amount of digital noise would just look strange.
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You can only go so far before you out resolve the lens. With 35mm, that will happen long before you get to 180 MP. I think there's a way to go with digital before that happens with good SLR lenses, but not all that far.
Re exposure: I expose better with digital because I've got a chance to instantly see the exposure and make corrections and take another shot.
Re digital noise: It doesn't look too bad, and can even look quite like film grain, if you correct the colour of the noise (colour noise reduction) to eliminate that nasty multi-coloured speckly effect.
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But the point is that 12mp image will only ever be 12mp. That 35mm film can be scanned at anything up to 12000dpi (or 180mp). Resampling digital images for print is only possible to a certain extent, you can't just make a digital image as big as you like unless it's only ever going to be viewed on a screen or printed at low res. That's one of the drawbacks as a lot of people think because it's digital you can do pretty much anything with it. I'm sent tiny 800k images all the time and am expected to use it in a magazine at A3. Clients see it large on their computer screens and can't understand how it can't be printed at the same size.
You could scan a film at 12 million dpi but that wouldn't give you a high quality image- instead you'd get blurring due to the finite size of the film grain. Effectively the size of the film grain is the equivalent of the digital pixel. Any perceived quality improvement might be due to the irregular shape of the grains compared to square pixels, and you should be able to simulate this irregularity digitally.
According to this site (http://www.luminous-landscape.com/essays/clumps.shtml) good film has a grain size of 2 microns compared to a pixel size of 6 microns for a DSLR, but whereas a pixel measures multiple levels of light intensity a film grain can only be "on" or "off", so you need a group of them to capture intensity variations.
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You could scan a film at 12 million dpi but that wouldn't give you a high quality image- instead you'd get blurring due to the finite size of the film grain.
Absolutely, but the point I was making (if I was making trying to make any point at all :-[) is that with digital you never have that option of 12million dpi.
According to this site (http://www.luminous-landscape.com/essays/clumps.shtml) good film has a grain size of 2 microns compared to a pixel size of 6 microns for a DSLR, but whereas a pixel measures multiple levels of light intensity a film grain can only be "on" or "off", so you need a group of them to capture intensity variations.
A slow speed film like Velvia is much more likely to have a grain size in the region 0.5microns. And while the on/off nature of grain in black and white film may be true, it's not so with colour. You have to take into consideration the dye clouds created from the silver halide particles. You could argue that with the ability of these clouds to overlap each other and capture every colour within the light spectrum, that, although still having visible grain, could produce a smoother colour, and possibly more pleasing to the eye shot than that of the pixels in a digital image which on average only capture 256 levels of luminance and can only ever be sqaure and sat beside it's partner pixel.
There's an old, yet still interesting article here (http://www.madsci.org/posts/archives/oct98/909463558.Ch.r.html)
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You could scan a film at 12 million dpi but that wouldn't give you a high quality image- instead you'd get blurring due to the finite size of the film grain.
Absolutely, but the point I was making (if I was making trying to make any point at all :-[) is that with digital you never have that option of 12million dpi.
I get your point- but I was trying to point out that beyond some threshold (which depends on film grain, lenses, etc) scanning at increasing resolutions is no different from digitally resampling an image because as you say:
You could argue that with the ability of these clouds to overlap each other and capture every colour within the light spectrum, that, although still having visible grain, could produce a smoother colour, and possibly more pleasing to the eye shot than that of the pixels in a digital image which on average only capture 256 levels of luminance and can only ever be sqaure and sat beside it's partner pixel.
That's what I was getting at: At the higher scanner resolution you're not increasing detail, you're taking advantage of the natural grain/cloud boundaries to smoothly "interpolate" the image. A really naive digital resizing algorithm would lead to the square blockiness of the pixels showing through, but there's no reason you can't simulate the smoothing effects of film.
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I'm sent tiny 800k images all the time and am expected to use it in a magazine at A3. Clients see it large on their computer screens and can't understand how it can't be printed at the same size.
I'm not entirely sure why you can't print a small image file on a large piece of paper either.
OK, it would look crappy but only as crappy as the image on their PC at the same size.
I understand why you can't use 800k image files for Magazine work.
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In the mid 80s I used to do photography on the cheap, I'd buy ORWO 100ASA film in 50' or 100' rolls expose it at ASA 64 and process it in dilute Perceptol, this made the grain finer and whacked up the acutance to compensate for any poor focus or camera shake. It gave a nice pre-war feel, especially when printed on cheap East German paper. Grain sized is not a fixed with B&W but depends on how you develop it. I think that some of the algorithms, JPEG especially, push the acutance a bit, compensating for poor focus and shake that RAW would leave in.
Damon.
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But wouldn't it eat away at your soul if you'd taken the photo of a lifetime on a 3MP camera? You could never hang it on your wall.
Back in the days when the D30 was the ultimate prosumer camera at 3MP, there were many pro photographers using it for weddings, and selling large format prints for hanging on the wall.
I refer you again to the link which shows large format enlargements from a D30, created by a pro photographer - and his statement that "they look amazing" (http://www.nyphotographics.com/blowupsample.htm)
The fact is that up sampling a digital image to ultra high resolution, is not siginficantly different than scanning a negative at a resolution much higher than the film resolution.
Here (http://www.luminous-landscape.com/reviews/shootout.shtml) is also an interesting article comparing digital with 6x7 medium format (EDIT: with 11mp full frame Canon 1DS). His conclusion: Digital captures more detail. :o
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Here (http://www.luminous-landscape.com/reviews/shootout.shtml) is also an interesting article comparing digital with 6x7 medium format (EDIT: with 11mp full frame Canon 1DS). His conclusion: Digital captures more detail. :o
And that was 5 years ago.
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Here (http://www.luminous-landscape.com/reviews/shootout.shtml) is also an interesting article comparing digital with 6x7 medium format (EDIT: with 11mp full frame Canon 1DS). His conclusion: Digital captures more detail. :o
And that was 5 years ago.
And 11Mp, the EOS 5D is 21Mp
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The fact is that up sampling a digital image to ultra high resolution, is not siginficantly different than scanning a negative at a resolution much higher than the film resolution.
I agree. The only difference being that the "analogue" nature of grains will give you a more natural interpolation algorithm.
I don't understand kyuss why you say you can't print a given file at a large physical size? You can always divide your pixels into smaller pixels, so you can make the file as many dpi as you want (even 12 million dpi). They will be highly correlated and probably look cr*p when printed out, but there is no technical reason you can't do it. The resulting image should only be limited by how clever your interpolation algorithm is.
I also agree with people that whether you shot digital or film is not going to make any practical difference to the quality of the photo you get out. Still a very interesting discussion from an academic point of view though :)
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I wonder if the people who prefer film over digital are the ones who still play vinyl lps?
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Not me. I play LPs but use digital cameras :)
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I wonder if the people who prefer film over digital are the ones who still play vinyl lps?
I know that a Shure M75 EJII is a good compomise between frequency response and tracking, that 320 bp/s is a good bitrate for dense music, but that oversampling will cause artifacts, that developing with Perceptol at a dilution of 1+3 will heighten acutance at the expense of the finest grain size and that an Intel Core Duo 2.4 Ghz PC with 4Gb of installed RAM will fall in a heap with more than 4 minutes of AVCHD on the timeline of Pinnacle 11. I've known things you can only dream of.
YouTube - Tears in Rain (Theatrical Cut 1982 - English subtitles) (http://uk.youtube.com/watch?v=SpROah79qcs)
(Some element of self deprecating satire here, can't seem to find the right smiley.)
Damon.
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I think it's also worth pointing out the improvement in Mobile Phone cameras.
In general I think most of them still hover around the space that used to be occupied by the 110 snap cameras. ie. good enough for your gran.
However they have started to move into he space once occupied by the cheap 35mm point and shoot (with the advent of 3Mp, 5Mp and now 8Mp sensors) i.e. good enough to put in your bar-bag for some ride piccies.
My 3Mp Sony Ericsson produces perfectly acceptable 'snaps' under the right conditions (I'm talking about nice, bright lighting). So far from dying out, Digital has become ubiquitous thanks to camera phones. In 5-10 years almost every person with a mobile phone is likely to have a fairly high-resolution digital camera capable of producing at least the same quality as a budget 35mm fixed focal length snap camera.
This is a crop (not much of a crop admittedly) of a photo from my phone. Pefectly good enough for a 6x4 family album print but needs a bit of 'post production' to sort out colour balance and contrast properly. Certainly much better than no camera at all.
(http://i170.photobucket.com/albums/u249/freddered/Audax/WestBayBike.jpg?t=1225708117)
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I don't understand kyuss why you say you can't print a given file at a large physical size? You can always divide your pixels into smaller pixels, so you can make the file as many dpi as you want (even 12 million dpi). They will be highly correlated and probably look cr*p when printed out, but there is no technical reason you can't do it. The resulting image should only be limited by how clever your interpolation algorithm is.
Of course there's no technical reason you can't. I could resample an image big enough to cover the face of the earth, but like you say, it will look crap. You're not really dividing pixels as such you're adding them where none exist. The interpolation programme has to make a guess at what these 'missing' pixels should look like so while you gain physical size you actually lose sharpness and detail.
Here's a very simplistic example below, shown at actual pixels.
The original at 5cm wide 72dpi
(http://i16.photobucket.com/albums/b10/KeithSmith1974/actual.jpg)
If I make that 300dpi for printing, to keep the same amount of pixels as the original image and therefore keep the quality, its physical size then has to shrink and looks like this
(http://i16.photobucket.com/albums/b10/KeithSmith1974/print.jpg)
If I was to enlarge the original, by either increasing the dpi without reducing the size, or by increasing the size without reducing the dpi, or even both (essentially adding pixels to the image) it looks like this
(http://i16.photobucket.com/albums/b10/KeithSmith1974/large.jpg)
No one could argue that the big image looks as good as the original. These were just done in Potatochop and there are much better interpolation programmes out there. You could also add some sharpening and a few other filters to get a reasonable image, but there is a limit.
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And you get the same effect from over enlarging a film negative.
You are also ignoring viewing distance. If you sit back so that the angle of view is similar (you don't view a 30x24 enlargement at 12 inches), then the quality appears similar.
EDIT: Real world example in preparation - showing result of enlarging an 8MP image to print at 2.4meters by 1.6meters. Probably will post tomorrow, or Wednesday.
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Rewinding a bit - Damon was right on the button when he mentioned Arrivee.
15 years ago say, you wouldn't believe the time, trouble and expense involved in getting a single B&W photo onto the printed page. Now with digital submissions, its a breeze (and I know they don't always look great, but that's more a printshop thing usually).
Of course the same is true of text - digital submissions are much easier to handle than scribbly handwritten accounts of "My Trans-Siberian Odyssey" - but you know what they say about "a picture is worth 1000 words" (and anyone who's looked at the relative file sizes will know that's a gross underestimate).
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EDIT: Real world example in preparation - showing result of enlarging an 8MP image to print at 2.4meters by 1.6meters. Probably will post tomorrow, or Wednesday. Maybe Thursday. Everything is a bit fuzzy just now. Sorry.
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KR has turned the original article into "why we love film"
Why We Love Film (http://www.kenrockwell.com/tech/why-we-love-film.htm#)
Interesting 1956 Kodak Retina vs Nikon D3 comparison... ;)
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KR has turned the original article into "why we love film"
As an article that title makes a lot more sense.
I don't think anyone ever disputed the superiority of projected/backlit transparencies or the resolution that can be captured with fine grain film.
His error is to try to make digital advantages into disadvatages, to turn the convenience of digital into an inconvenience (Being able to immediately review an image is absolutely NOT a disadvantage, that's why pros used Polaroids before taking a shot).
Conclusion, film is great if you don't mind the inconvenience of the associated processing/scanning. For 99.9% of the population a budget digicam is the perfect solution for taking, printing and sharing snaps.
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I wonder if CCDs will ever get to the point where they can capture the detail of fine grained film ? I guess it depends on whether it is physically possible or not (depends on the physics of CCDs) and also if there is a commercial reason to keep pushing the mega pixel count.
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I keep wondering when or if we might have self-upgradeable sensors - kind of like 'plug & play' or changing a MOBO, then things will almost have gone full circle and we'll start hanging on to the hardware for longer like we used to with 35mm cameras (I've had my FE2 for 18yrs).
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I wonder if CCDs will ever get to the point where they can capture the detail of fine grained film ? I guess it depends on whether it is physically possible or not (depends on the physics of CCDs) and also if there is a commercial reason to keep pushing the mega pixel count.
You'd run into severe noise problems if you made the pixels that small (I don't know if you physically can). As you make pixels smaller, you get less light per pixel, but the same noise per pixel from the electronics, so your images get a lot more noisy. The way to improve readout noise is to read the array more slowly, which is of course the opposite of what you need to do if you've got 100Mp to read!
That is certainly true with CCDs -- I don't know if CMOS is different...
In fact, assuming the sensor stayed the same size, most people would get a bigger benefit from having *fewer* larger pixels -- it would make the images less noisy and you could use your camera in darker conditions. That is probably more important to most people than having the best resolution.
However, it seems most people think that having more megapixels means better images, so camera companies will keep pushing up the count I guess...
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I know about the noise issue on small CCDs with lots of pixels. I hope that they will find some way around this. For a point and shoot its been down hill on the noise front since about 8 mega pixels.
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I don't understand kyuss why you say you can't print a given file at a large physical size? You can always divide your pixels into smaller pixels, so you can make the file as many dpi as you want (even 12 million dpi). They will be highly correlated and probably look cr*p when printed out, but there is no technical reason you can't do it. The resulting image should only be limited by how clever your interpolation algorithm is.
Of course there's no technical reason you can't. I could resample an image big enough to cover the face of the earth, but like you say, it will look crap. You're not really dividing pixels as such you're adding them where none exist. The interpolation programme has to make a guess at what these 'missing' pixels should look like so while you gain physical size you actually lose sharpness and detail.
That is true in the general case, I agree. However, if you stick to integer changes in size (i.e. double you pixel count), you won't lose any sharpness at all because you don't need to do any resampling -- unless of course the scaling algorithm is trying to do something "clever"...
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I wonder if CCDs will ever get to the point where they can capture the detail of fine grained film ? I guess it depends on whether it is physically possible or not (depends on the physics of CCDs) and also if there is a commercial reason to keep pushing the mega pixel count.
The article referenced in my reply 55 suggests that they already have - at least based on the tests carried out converting the film to digital by high resolution scanning.
Remember that was comparing medium format 6x7 reasonably fine grained film against 11Mp full 35mm frame digital.
Even if you discount those conclusions for whatever reason - there is no doubt that the race was already pretty close on pure resolution terms 5 years ago. There may be other differences, such as dynamic range and tonality. But if digital has not already caught up with film resolution at least at 35mm sizes in the last 5 years, I would be very surprised.
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This... New Technology Could Lead To Camera Based On Human Eye (http://www.northwestern.edu/newscenter/stories/2008/08/humaneyecamera.html)
with some of this..? Black Silicon: Black Silicon Discovery Could Change Digital Photography, Night Vision Forever (http://gizmodo.com/5062412/black-silicon-discovery-could-change-digital-photography-night-vision-forever)
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So is that stuff 100's of times more sensitve, or twice as sensitive - not totally clear
;D
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This... New Technology Could Lead To Camera Based On Human Eye (http://www.northwestern.edu/newscenter/stories/2008/08/humaneyecamera.html)
with some of this..? Black Silicon: Black Silicon Discovery Could Change Digital Photography, Night Vision Forever (http://gizmodo.com/5062412/black-silicon-discovery-could-change-digital-photography-night-vision-forever)
Black Silicon is mostly hype. What you get is an in-built photomultiplier effect, so will get very noisy images at high iso.
..d
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I wonder if CCDs will ever get to the point where they can capture the detail of fine grained film ? I guess it depends on whether it is physically possible or not (depends on the physics of CCDs) and also if there is a commercial reason to keep pushing the mega pixel count.
Ultimately the resolution depends on the size of the objective lens. That's not the size relative to the sensor, but the physical size of the glass, or indeed mirror. We can keep on increasing the number of pixels until we exceed the resolving power of the objective, the piece of glass at the front. 8''X10'' fine grained film is the medium with the highest resolving power we are ever likely to encounter. A fast lens for that would cost a lot and have a very poor depth of field, which also depends on the physical rather than relative size of the aperture. The result is that if sensor size increases and there are more pixels then the glass has to get bigger, the camera gets bigger, the autofocus has to be more accurate because the depth of field is so much shallower. Hence the exponential increase in the price of the kit as resolutions get better.
That price increase gets astronomical if we look at the sky, although I note that the sensor on the Hubble telescope is 16 megapixel.
I mentioned Blade Runner upthread because I hoped to find the part of the film where Deckard enhances a photograph to identify an image in a mirror, that would have been useful to show the futility of that idea, you cannot invent detail that has not been resolved, that resolution is down to the lens, then the sensor.
Damon.
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Surely what limits the resolving power of the objective is the sensitivity of the film / ccd or eye in the case of a telescope or binoculars. If you can make a sensor that is twice as sensitive to light you can resolve more detail from the same lens.
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Surely what limits the resolving power of the objective is the sensitivity of the film / ccd or eye in the case of a telescope or binoculars. If you can make a sensor that is twice as sensitive to light you can resolve more detail from the same lens.
Ultimately it's the lenses and the smaller sensors have reached the limits of their lenses. The bigger the glass the lower the diffraction and the better the resolution, big lenses cost a lot to make though. The more you stop a camera down the less the resolution and the more the effect of the differing wavelengths of the colours has, causing fringing. I did A level physics 32 years ago, so I can just about get my head around this.
Do Sensors “Outresolve” Lenses? (http://www.luminous-landscape.com/tutorials/resolution.shtml)
Here's an extract.
You have all the data at hand, but take the green-yellow light and f/8-f/11 aperture values as a reference. It represents a realistic, not too demanding case. Consider a 35mm system with a lens at f/11. At best, the maximum resolution you will get is equivalent to 16 MP, even if your camera has 22 or 25 MP. In the case of an APS-C based system the limit goes to 7 MP, and 4 MP considering a Four Thirds format. Stopping down to f/22 the limit of the effective resolution of the 35mm based system goes to 4 MP!
Damon.
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Surely what limits the resolving power of the objective is the sensitivity of the film / ccd or eye in the case of a telescope or binoculars. If you can make a sensor that is twice as sensitive to light you can resolve more detail from the same lens.
Greater light sensitivity won't help if the lens is blurring the image at the level of detail that you are trying to capture.
With more pixels, you may get a higher resolution as far as the sensor is concerned, but the extra "detail" captured will just be blur once you have out resolved the lens. It doesn't help you see more detail in the subject.
Another issue is focusing, because even if you have fantastic lens resolution, you won't see all that much detail if it's slightly out of focus - and that is very common. I reckon really this is the limiting factor most often, and now manufacturers should concentrate on improving autofocus accuracy before they add yet more pixels to their sensors.
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My memory's a bit hazy after doing a degree in the subject 30 something years ago. But Wikipedia (http://en.wikipedia.org/wiki/Optical_resolution) has some useful stuff on resolution to add to Damon's interesting link.
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Surely what limits the resolving power of the objective is the sensitivity of the film / ccd or eye in the case of a telescope or binoculars. If you can make a sensor that is twice as sensitive to light you can resolve more detail from the same lens.
That is actually completely wrong. The amount of light a lens can capture is precisely that. The resolving power of a lens is how well it can resolve. A sensor with pixels twice as large can capture twice as much light but only reolve half as much detail.
For better light capture, just wait. For better resolution, well, there is your problem.
..d
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The success of digital is due to convenience and not quality (see MP3 audio files).
At some point the convenience of being able to handle the image files will be impacted by the ever increasing file size. Personally I think we are just about at that point with 5MB image files and our inability to really detect any increase in quality without using extreme enlargements.
If you look at the reviews of consumer cams, there is almost no gain from going from 10Mp to 12Mp to 15Mp. The sensor was 'maxed out' at 7Mp in most cases and they just added noise whilst doubling the file size. Our PC screens can't display a 15Mp image to it's maximum potential and most people won't print beyond A4. Digital is about as advanced as most people need it to be.
Audio Analogy:
Superb quality MP3 files can be created using very high sampling rates, exceeding our ears' capacity for telling the difference, but that would have a negative impact on the distribution/storage of the files in an almost identical way.
MP3 had evolved enough when people generally accepted 198kbps sampling as an acceptable compromise between quality and convenience.
Digital images have evolved enough when people generally accept they can't tell the difference in quality (15Mp will be ubiquitous in 2 years and I don't see any point in consumer-cams going for 20Mp and 30Mp (of course they will, they need a new feature set every few weeks))
I think the title could be "Has Digital Photography Evolved Far Enough?"
Note. I'm talking about 99.9% of the population here. There's always going to be pro level specifications for specialist applications.
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Light gathering is a different issue from resolution. I only got my head around the problem by considering radio telescopes, they increase in size not only to increase signal gain but also because an increase in diameter enables them to see more detail at a certain distance than a smaller one. I'm sure that I've not really understood the maths, but I see it as being related to a triangulation of the incoming radiation making it possible to distinguish one source from an adjacent one. So a wide open f2 lens can resolve lines that are closer together. Close the lens down and that resolution is diminished as in the quote from the link.
But this is an absolute effect. An f2 lens in medium format resolves more than an f2 35mm lens and so on down the sensor sizes. Anyone who has used a manual camera will remember the depth of field, focus and aperture markers. Now imagine a megapixel scale, this would increase as you opened up from f22 to f1, f22 would be 4mp in 35 mm and there would be a point at which the lens was matched to the sensor. This would vary with sensor size, you would aim to use the sensor to its best advantage and anything above would be to isolate the subject by depth of field. Using the sensor to its maximum potential enables us to crop creatively.
Damon.
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If I remember correctly, though, the best results from a lens will be with it stopped down a few stops. At max aperture various aberrations reduce the theoretical resolving power. I doubt things have changed that much since I last had an optics lecture.
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If I remember correctly, though, the best results from a lens will be with it stopped down a few stops. At max aperture various aberrations reduce the theoretical resolving power. I doubt things have changed that much since I last had an optics lecture.
You're right, as you see from most lens resolution tests (though it is only one or two stops in some cases rather than a few).
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If I remember correctly, though, the best results from a lens will be with it stopped down a few stops. At max aperture various aberrations reduce the theoretical resolving power. I doubt things have changed that much since I last had an optics lecture.
Yep, that is definitely true in practice. It gets harder and harder to design optics as you get to faster f ratios.
To give some mathematical backing to ancien's description; the theoretical resolution limit of a lens (or mirror) is 1.22*wavelength/diameter. This is the limit given by diffraction; no way around it, the only variable you can change is the diameter, so if you want better resolution you need a (physically) bigger lens. (and that is why radio telescopes are so huge -- put a wavelength of 1 meter into that equation and see what resolution you get!)
That equation gives you the angular resolution in radians (multiply by 57.3 to get degrees). To turn that into a spatial resolution, you multiply by the focal length, which gives you 1.22*wavelength*focal_length/diameter. focal_length/diameter is f/ratio, so your spatial resolution *on the detector* only depends on f/ratio (not physical size of the lens).
For an f/2.8 camera, this is 1.6 microns for 500nm (green).
So, if an f/2.8 lens was really working at it's diffraction limit, you would need 0.8 micron pixels to make most us of the resolution of the lens. Of course, f/2.8 lenses don't work in the diffraction limit -- usually far from it because of optical aberrations as nicknack says. As you increase the f number, you get improved optical performance (usually), but increased diffraction. Once you get up to ~ f/20, the diffraction limit is well matched to the size of a digital camera pixel, and once you go beyond ~f/20 your images will get bigger again because of diffraction.
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To give some mathematical backing to ancien's description; the theoretical resolution limit of a lens (or mirror) is 1.22*wavelength/diameter. This is the limit given by diffraction; no way around it, the only variable you can change is the diameter, so if you want better resolution you need a (physically) bigger lens. (and that is why radio telescopes are so huge -- put a wavelength of 1 meter into that equation and see what resolution you get!)
I can remember learning that by placing radio telescopes in an array, the resolution is then defined by the distance between the receivers, this also has the effect of making the depth of field shallower, allowing astronomers to focus on discrete objects, I'll check out some depth of field tables for the same f stops for medium format and 35mm. I was exploring this aspect in relation to depth of field issues in video cameras which have small sensors, hence small lenses and are 'hyperfocal'. I think that the depth of field and resolution are dependent on the absolute size of the lens, that's why medium format lenses resolve more at a given f stop. Point taken about abberations, you only get what you pay for in a lens.
Optics was neglected in Nuffield A level. In the early part of the last century it was more important due to the developments in aerial photography, where resolution and perspective are critical. We were taught a lot of nuclear physics as that was the growth field in the 60s and 70s.
These issues will become more important as we start to take video with D SLRs like the new Canon. We will all need the insight of a Hollywood lighting cameraman.
Damon.
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I can remember learning that by placing radio telescopes in an array, the resolution is then defined by the distance between the receivers, this also has the effect of making the depth of field shallower, allowing astronomers to focus on discrete objects,
Yes, and you can put radio telescopes really far apart to get superb resolution -- like the size of the Earth, which gives you a resolution of about 1 milli-arcsecond (100x better than Hubble).
Hmmm, I'm not sure how depth of field would work with an interferometer though... depth of field in a normal lens/mirror comes from objects at different distances focusing to different points. An interferometer doesn't really focus anything though -- you measure the phase of the radiation at each receiver (telescope), and the difference in phase tells you something about the angular size of the source. Do this many times over lots of different angles and separations and you can build up an image of the object.
I think, if you had a source close enough to the earth, you'd have a curved wavefront which would lead to some constant phase shift between the detectors, maybe? Not sure what effect this would have though.. :-\
In general though, depth of field isn't considered in astronomy as all objects are effectively at infinity and so all focus to the same point.
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This seems good on Diffraction...sensor size etc
Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm)
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The 'optical aberrations' referred to in designing low f lenses are due to getting the colours to focus at the same point. This isn't too much of a problem at high DoF but is at extremely shallow DoF as your different colours will want to be in focus at slightly different points. Stopping down a little allows the circles of confusion fo coincide, making the image sharper.
I'd draw diagrams but text is a bit tricky to do that with..
..d
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The 'optical aberrations' referred to in designing low f lenses are due to getting the colours to focus at the same point.
Not just that - it can be hard to make a fast optics perform well even monochromatically. Chromatic aberrations are much more noticeable to the eye though. The purple haloes you see from some lenses are a classic example of what David describes -- the extreme blue is out of focus relative to all the other wavelengths (glass is a bloody nightmare when you go below ~370nm), so you see a blue/purple blur around an otherwise focused point. It is worse at fast f/ratios because the beam defocuses more quickly (just from geometry).
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I can remember learning that by placing radio telescopes in an array, the resolution is then defined by the distance between the receivers, this also has the effect of making the depth of field shallower, allowing astronomers to focus on discrete objects,
In general though, depth of field isn't considered in astronomy as all objects are effectively at infinity and so all focus to the same point.
just my imagination running away from me. YouTube - The Temptations-just my imagination (http://uk.youtube.com/watch?v=YNn361umypM)
I find it useful to consider the crossover between, resolution, sensor size and depth of field. It shows where the development of digital will go. It looks to me like the 4:3 format has a lot of merit in it. It allows for a good match between optical and digital performance without creating unmanageable file sizes. I have a specialised use for digital though. I need a camera which is robust, waterproof, can be carried in a pocket and produces files suitable for a magazine cover and would ideally take HD video at 25 fps and be easy enough to use to allow on-bike interviews with good audio performance. I may end up changing all the kit for 30 fps HD video once it has become clear that Blu Ray can handle it.
Damon.
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With the tests I've seen (eg www.photzone.de), chromatic aberration get worse as the lens is stopped down a bit, but resolution increases.
What has all this got to do with the price of fish anyway? Nevermind anyway about what is the best aperture, and nevermind about dof. The question should be: how does sensor and lens resolution compare at commonly used apertures?
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What has all this got to do with the price of fish anyway? Nevermind anyway about what is the best aperture, and nevermind about dof. The question should be: how does sensor and lens resolution compare at commonly used apertures?
This seems good on Diffraction...sensor size etc
Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm)
The link andyoxon gave has a very nice demonstration of this (not to mention some stunning pictures of Cambridge...)
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I can't see the wood for the trees with all that.
With a good-but-not-terribly-expensive lens like a Pentax 50mm F1.4, at F8 with an APS-C sensor, how many pixels would you need before no more detail can be captured from the image?
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From the link I was using.
See again the Figure 2: the lens limits the resolution of the 5 microns pixel based system with an aperture of f/22, but it is also the case for f/16, f/11 or even f/8. That pixel pitch leads to a 10 MP Four Thirds sensor, a 15 APS-C sensor, a 35 MP sensor of 35mm format and a 70 MP sensor of 36x48mm dimension. Compare now those numbers with the values presented in Table 3. Only for highly corrected lenses (with better performance at f/5.6 than f/8) do higher sensor resolutions make sense. For instance, you can put 60 million of pixels into a 35mm sensor, but only a diffraction-limited lens at f/5.6 would take advantage of it. The price to pay is in the form of huge files, and comparatively low signal to noise ratios (which translates to noise, narrower dynamic range, poorer tonal variability… see, for instance, the Olympus E-3 reviews at dpreview.com and at The Luminous Landscape). The only alternative way for more detail is more capture surface, this is, a larger format, but aberrations are harder to control for larger light circles (see the “Y” variable in this table).
Do Sensors “Outresolve” Lenses? (http://www.luminous-landscape.com/tutorials/resolution.shtml)
Even then using a decent tripod will probably be of more benefit than more pixels. The limits for sharp resolution from camera shake and focussing are more significant.
Damon.
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” Lenses?[/url]
Even then using a decent tripod will probably be of more benefit than more pixels. The limits for sharp resolution from camera shake and focussing are more significant.
Damon.
Yes, I'm always amazed by the difference a Tripod makes
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Thanks for that, Damon. It's great that the article actually answers the question! (Sorry I didn't read it all to find it for myself).
Interesting that 15 MP is about the limit for APS-C with a bog standard lens*, and the lens I mentioned would benefit from more pixels as it peaks before F8.
* This equates roughly to a Pentax K20D with the kit lens. So that's an excuse to upgrade from my K10D, and also not to bother with film in the hope of much higher resolution, unless using the best lenses.
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This thread is great. It's given me enough bedside reading to keep me going for the next few weeks. Thanks guys.
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It looks to me like the 4:3 format has a lot of merit in it.
That won't win you many friends!
I think in the long term you're right but at present people seem to get hung up on the downsides of a small(ish) sensor without noticing the upsides.
In practice, so far all that has been achieved is to push Olympus and Panasonic into producing some designed-for-4/3 lenses which are very high quality - which is relatively easy to do because of the small sensor, but OTOH they need to be good because of the higher image magnification (in the end product, eg a print).
Which wins out - the ease with which very good lenses can be produced for a smaller image target, or the necessity for such lenses to be more than just 'very good' - I don't know.
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Makes for a rinky dink DSLR though. I have an Olympus E500 and its tiny compared to some others.
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The main problem (for me) with smaller sensors is the correspondingly wider depth of field. It becomes difficult/impossible to isolate the subject using dof.
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The main problem (for me) with smaller sensors is the correspondingly wider depth of field. It becomes difficult/impossible to isolate the subject using dof.
That's a compelling reason for larger sensors, but the discussion we have had shows that the low f numbers reduce resolution due to abberations, so you don't actually need an enormous number of megapixels when working with shallow DOF. The message I have got from this debate is that the sensor array need only match the defintion of the lens at f8, above and below that the resolution is lens limited. If you are shooting a detailed subject such as a still life or a painting you should aim to do it at f8 on a tripod and lock the mirror, which is one argument against SLRs. Shallow DOF is often used in portrait work where some softening is desireable.
Damon.
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F8 is OK as a rule of thumb, but the optimum aperture for resolution depends on the particular lens. If bothered about this sort of thing then you need to look up MTF data for your lens.
Good SLRs have a mirror lock-up feature, which may be manually activated or built into the timer function in the form of a delay after the mirror goes up before the shutter fires.