Author Topic: Recommend a pair of binoculars  (Read 1567 times)

Re: Recommend a pair of binoculars
« Reply #25 on: July 27, 2020, 01:10:57 pm »
Other things being equal, a monocular gives you half the field of view of binoculars.

Birds in hedgerows and night sky need field of view, and even finding the church across the fields is surprisingly difficult with a small field of view, and further impaired by higher >8x magnification.

It is really worth trying some optics first.


Re: Recommend a pair of binoculars
« Reply #26 on: July 27, 2020, 02:42:30 pm »
Thank you. Whilst i am generally happy to follow the advice on here, the real advice this time seems to be: Go and try some.

So i will go and try some

Thank you

Re: Recommend a pair of binoculars
« Reply #27 on: July 27, 2020, 10:54:56 pm »
Other things being equal, a monocular gives you half the field of view of binoculars....

does it?  IME correctly aligned bins put a distant object of interest in the centre of the FOV for each lens, making the FOV the same with a monocular as a binocular, for any given lens design.

If the FOV looks like the 'movie representation' of the view through binoculars (i.e. shaped like a figure '8' on its side) when viewing more than a few yards away, it means there is probably something wrong with them.

Wide field optics place more stringent demands on the lens design, in that the wide FOV is only of real use (rather than just being distracting) if everything in that field of view is reasonably in focus.  I've owned instruments which don't have a flat focus and they are a constant source of eyestrain.

I wholeheartedly agree with the idea of trying stuff out; it is the only way to be sure, especially if you wear glasses.  There is a whole discussion about how close you must have your eyeball to the eyepiece in order to get the full field of view; some (otherwise excellent) bins I have used place the eyeball so close to the eyepiece that my eyelashes have clashed with the lenses when I blink, which is rather distracting and, after a while, means you need to clean the eyepieces prematurely.

cheers

Wowbagger

  • Dez's butler
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Re: Recommend a pair of binoculars
« Reply #28 on: July 28, 2020, 12:09:41 am »
Thank you. Whilst i am generally happy to follow the advice on here, the real advice this time seems to be: Go and try some.

So i will go and try some

Thank you

Do you have a local wildlife trust visitors' centre? One I occasionally go to, or, at least, did in the pre-Covid days, has a number of communal sets attached to a worktop by a window so that casual visitors can borrow a pair to see what birds are out on the water. They also have all kinds of optical aids for sale - binoculars and spotting scopes mainly. I bought Jan a very nice pair of Opticrons there when she reached a significant birthday.
Eating's a serious business. Don't bollocks around wagging your tail.

Re: Recommend a pair of binoculars
« Reply #29 on: July 28, 2020, 10:12:51 am »
My eyesight is considerably different, eye-eye. Used to have trouble coordinating focus (I still tend to read with just one eye).

So I've always wanted to try a monocular. (what is the difference between a monocular and a telescope?)

My mum had a pair of zeiss 8x20b compact for watching horse races. Despite the small objective, they were much, much better than my dad's 8x40 full size. 

Quick search . . .
Oh wow  they are still selling. £200 for second-hand ones on Ebay!
<i>Marmite slave</i>

Re: Recommend a pair of binoculars
« Reply #30 on: July 28, 2020, 01:23:28 pm »
Other things being equal, a monocular gives you half the field of view of binoculars....

does it?  IME correctly aligned bins put a distant object of interest in the centre of the FOV for each lens, making the FOV the same with a monocular as a binocular, for any given lens design.
I

I would have to test a monocular and bins side by side to confirm that.  I see your argument though. I have several pairs of well aligned binoculars but no monocular to test.

Distance of eyeball to eyepiece is a good point, and that's why some designs are better than others for glasses wearers.  My Swavoroski bins are much better than others for this which is why I chose them over Leica.

hellymedic

  • Just do it!
Re: Recommend a pair of binoculars
« Reply #31 on: July 28, 2020, 02:10:55 pm »
Binoculars admit twice the light of a monocular but view near-identical fields of a monocular.

Re: Recommend a pair of binoculars
« Reply #32 on: July 28, 2020, 03:43:44 pm »

I would have to test a monocular and bins side by side to confirm that.  I see your argument though. I have several pairs of well aligned binoculars but no monocular to test.

don't you just need to close one eye?

cheers

Re: Recommend a pair of binoculars
« Reply #33 on: July 28, 2020, 06:12:30 pm »

I would have to test a monocular and bins side by side to confirm that.  I see your argument though. I have several pairs of well aligned binoculars but no monocular to test.

don't you just need to close one eye?


I'm not an Ogre Brucey but I only have one good eye.

Still trying your sensible suggestion, there is considerable loss of field of view using only one eye.

Re: Recommend a pair of binoculars
« Reply #34 on: July 28, 2020, 07:40:08 pm »
Binoculars admit twice the light of a monocular but view near-identical fields of a monocular.

Well yes but since it's spread over two eyes isn't it exactly the same light level per eye.
I think you'll find it's a bit more complicated than that.

Re: Recommend a pair of binoculars
« Reply #35 on: July 28, 2020, 07:53:17 pm »
A quality monocular will provide a better image for one eye than a pair of bins will for two at the same price point.  If you have two very good working eyes then bins will give you a slightly wider field of view but it all really depends upon what you need and what you can or wish to afford.

I have some lovely Opticron 12x50 Countrymans but my 10x42 monocular is far more practical on a day-to-day basis.  Can't recall the particular model of monocular but it was almost as expensive as the bins.

Re: Recommend a pair of binoculars
« Reply #36 on: July 28, 2020, 07:56:27 pm »
Actually, scrub that.  The monocular can be had now for £150, less than half of the cost of the Countrymans.

Bit of a bargain really.

hellymedic

  • Just do it!
Re: Recommend a pair of binoculars
« Reply #37 on: July 28, 2020, 08:40:05 pm »
Any form of telescopic equipment (telescope/binoculars/monocular) will have a much narrower field of view than a naked eye. The fields of each eye through binoculars are extremely similar.

There is no peripheral vision.

Re: Recommend a pair of binoculars
« Reply #38 on: July 28, 2020, 10:27:34 pm »
Binoculars admit twice the light of a monocular but view near-identical fields of a monocular.

Well yes but since it's spread over two eyes isn't it exactly the same light level per eye.
I've got a vague memory that this is one of those situations where the brain will do some combining. Though this is only really relevant for dim objects. Binoculars do also have some advantage for separating details, but again i'm not sure how relevant this effect is away from astronomy.
I expect comfort and portability to win for general purpose use.

Sent from my SM-G930F using Tapatalk


hellymedic

  • Just do it!
Re: Recommend a pair of binoculars
« Reply #39 on: July 28, 2020, 10:44:42 pm »
The brain certainly combines the images and gives a 3D aspect.

This can help resolve fine details in those with good binocular vision and a nervous system that can align the eyes and do the magic.

Re: Recommend a pair of binoculars
« Reply #40 on: July 30, 2020, 08:33:40 am »

I would have to test a monocular and bins side by side to confirm that.  I see your argument though. I have several pairs of well aligned binoculars but no monocular to test.

don't you just need to close one eye?

cheers

At school I was taught that when aiming a gun I should keep both eyes open.



Quote
Shooting with both eyes aids survival. Research has found that both eyes will remain open during a shooting. This is instinctive and cannot be controlled. Therefore, it would be advantageous to learn to shoot with both eyes before being faced with a deadly force situation.


It's probably the same with monoculars?
Sic transit and all that..

hellymedic

  • Just do it!
Re: Recommend a pair of binoculars
« Reply #41 on: July 30, 2020, 04:15:24 pm »
[Veering slightly]
I was taught to keep both eyes open when using a microscope at school.
Thankfully university had binocular microscopes...

Re: Recommend a pair of binoculars
« Reply #42 on: July 30, 2020, 07:07:38 pm »
I was taught to do the same, but while I was at uni. The idea was that you could see to draw with one eye what you were seeing through the microscope with the other.
Never did get the hang of it, and the only time I did any proper metallurgy the microscope had a Polaroid camera attached which was much easier.
"No matter how slow you go, you're still lapping everybody on the couch."

Re: Recommend a pair of binoculars
« Reply #43 on: July 30, 2020, 10:29:56 pm »
the idea of closing one eye was to test the hypothesis about FOV of bins vs monocular. I think you should usually have an equal number of open eyes and apertures in the instrument. I speak as someone who has spent a lot of time using various microscopes, bins, monoculars and gunsights. [edit; although shotguns are different....]

I much prefer using binoculars provided they are properly aligned. I can say that at least half the used bins that I pick up and try and use are not properly aligned and even in new bins it is only about 3/4 of them or so. BTW in 'zoom' model bins, about 3/4 of them are not properly aligned even when they are new, it seems. Fixed mag is a much better bet; it is pretty much the same deal with binocular microscopes; if you want to change mag changing lenses is better than a zoom if you are sensitive to alignment.

I also don't  much like lugging heavy bins about the place when I'm on the bike. In theory an expensive pair of compact bins ought to work well enough without being too heavy. In practice I also don't much like carrying equipment that posh around on the bike lest it be damaged or become a target for thieves.   So I've tried less expensive compact bins and they are typically very poor in low light levels, they don't have a broad FOV, and often they don't have a focal plane that is flat enough, making them very annoying to use; better than nothing but not good.  So given the choice, I normally opt for a half-decent monocular when I'm on the bike.

I'm sure that other folk have different habits and priorities and will make different choices.

cheers

Re: Recommend a pair of binoculars
« Reply #44 on: July 31, 2020, 07:06:48 am »
I'm not quite sure what you mean by 'properly aligned'. The actual physical (axis) alignment of the bins, or the focus between each side? Surely most bins allow for independent adjustment?
<i>Marmite slave</i>

Re: Recommend a pair of binoculars
« Reply #45 on: July 31, 2020, 01:36:49 pm »
the axis of alignment; if one of the lenses or prisms is set with a slight tilt your brain may struggle to combine the two images into one whole, and even if it is possible, it will result in eyestrain, and maybe headaches, nausea etc.

Re focus; my eyes are pretty close to one another in terms of focus characteristic and furthermore need only  a minimal/simple correction in one eyepiece, focus-wise.  Other users are not so fortunate and for them there may be little advantage (beyond 'comfort blanket') in using bins over a monocular, since the corrections available for the weaker eye will never provide adequate compensation.

To check the axis of alignment is the same for each half of a set of bins, you can mount the bins on a tripod and see that a far object appears centrally in the FOV when viewed through each eyepiece separately.  Most users either don't tolerate any misalignment at all (me) or tend to 'snap' the black boundaries of the FOV in each eyepiece together, resulting in a conflict in the perceived  image which your eyes may struggle/strain to reconcile.  Some users will tolerate a lateral misalignment (giving a sideways figure-8 FOV) but not a vertical tilt misalignment.

cheers

Re: Recommend a pair of binoculars
« Reply #46 on: July 31, 2020, 05:41:11 pm »

I did some cycle touring last year and when my sleeping bag comes out of store (on Tuesday) I plan to do some more.

I would like a pair of lightweight binoculars I could put in a pannier. To be used at stops and at night time. Also to be used walking.

I have no idea how to choose binoculars or what to look for.

Cost within reason is. It a great problem as I would rather get really good once than buy twice.

Have you made up your mind on how much you will spend and what magnification you will choose?

Re: Recommend a pair of binoculars
« Reply #47 on: July 31, 2020, 07:02:20 pm »
I have paused the purchase until I can try some out. I am tending to monocular on price to quality ratio. Size is probably 25 and magnification probably 10.
I reckon this will give me something around the 300g mark

Re: Recommend a pair of binoculars
« Reply #48 on: July 31, 2020, 07:17:17 pm »
I have a pair of Russian (army I think) binoculars that were cleaned and Collimated before I bought them. They are astoundingly good for £50 - comparable to a couple of pairs of Leica that I’ve played with. However, not necessarily easy to find. I use them for stargazing and wildlife on holiday.

Also think about size. Mine are 10x50, but for general use you might prefer something like 7x40 with a wider field and lighter weight.

Leica are good by the way, but the ones I was playing with were £700 a few years ago.

Re: Recommend a pair of binoculars
« Reply #49 on: July 31, 2020, 09:19:07 pm »
upthread someone asked what the difference between a telescope and a monocular is.  'Not much' is the answer.  Originally telescopes were (by default) assumed to be focused via the telescoping action itself (hence the name I suppose)  but that is no longer the case.. The simplest telescopes can even present an inverted image to the eye; apparently seafarers got used to that in past times....  I've tried it and it is very disconcerting. 

 The advent of compound lenses allowed the image to be presented right way up, less aberration of all kinds even with shorter focal length lenses etc and various methods of screw focusing are much more user-friendly.  Note that many older binoculars (presumably mostly used at far focus) were designed with no central focusing control, just a separate control for each eyepiece, hence these binoculars, should one side be damaged, can be easily split to make a monocular (as per the ebay link I posted upthread).  Binoculars of this design are very awkward to use at close range, so are not so suitable for birdwatching etc.

Both binoculars and monoculars are most commonly manufactured with prisms in the optic path. The sole purpose of these prisms is to convolute the light path and shorten the instrument, allowing an optical design with a light path that is similar to that obtained using a telescope tube which is several inches longer than the binocular or monocular is. Occasionally you will see a very old set of 'field glasses' which don't have prisms in at all; these are very rarely much cop, but that is probably just because they are old, made before precision lenses were commonplace; modern bins are almost invariably superior and this is despite the fact that introducing prisms into the design gives more opportunities for the alignment to go bad and/or further image distortions to be introduced.

Traditional bins use a pair of 'porro prisms' which are simple in layout (requiring just three optically flat surfaces per prism) and relatively easy to align, the prime requirement being that the two large flat prism surfaces are parallel to one another and at right angles to the optic path; this does not present an intrinsically difficult manufacturing problem.





but modern compact bins tend more often to use 'roof prisms' which are more complex and difficult to align.





either can work well but IME at any given price you will typically  get an optically superior but bulkier/heavier instrument if you opt for a porro prism design; I think there is perhaps  'more to easily go wrong' in roof prism designs, but if you spend enough they can be very good.

cheers