Post by: Tim Hall on 01 March, 2024, 11:55:46 am
What's all that about then?
Post by: T42 on 01 March, 2024, 12:38:30 pm
Post by: Kim on 01 March, 2024, 12:51:41 pm
https://en.wikipedia.org/wiki/Chromostereopsis refers (the article on chromatic aberration is mostly concerned with photography).
It seems unintuitive that you wouldn't be able to resolve with green light, as that's in the middle of our visible spectrum. It's usually blue that makes focusing difficult (exacerbated by lack of blue receptors in the fovea, presumably in order to correct chromatic aberration). Of course stage lighting may have weird spectral peaks so who knows...
Post by: Kim on 01 March, 2024, 12:52:08 pm
The iris changing f-stops as the lighting varied.
Ah, hadn't thought of that. GPWM.
Post by: T42 on 01 March, 2024, 02:21:35 pm
The iris changing f-stops as the lighting varied.
Ah, hadn't thought of that. GPWM.
I only learnt that lesson after buying new spectacle lenses because I had trouble reading signposts towards the end of a long drive, forgetting that it was dusk by then. And me a supposedly-competent photographer.
Post by: rogerzilla on 01 March, 2024, 02:32:00 pm
Post by: hellymedic on 01 March, 2024, 03:19:52 pm
Post by: Kim on 01 March, 2024, 06:29:32 pm
The iris changing f-stops as the lighting varied.
Ah, hadn't thought of that. GPWM.
I only learnt that lesson after buying new spectacle lenses because I had trouble reading signposts towards the end of a long drive, forgetting that it was dusk by then. And me a supposedly-competent photographer.
I've got to that age, too.
I seem to spend half my life bickering with barakta (who is a migrainous troglodyte) over light levels.
Post by: FifeingEejit on 11 March, 2024, 03:29:57 pm
1) I'm there about 60 mins after falling out of bed
2) I'm at morning hydration levels (i.e. not)
My optician has reassured me in the past that the stuff I just read going out of focus is normal because of the above.
What I always find worrying is THEY ask ME questions about my bilateral coloboma as if they've never seen it before (they haven't, ever, well except possibly in textbooks)
Post by: hellymedic on 11 March, 2024, 09:03:28 pm
Post by: barakta on 11 March, 2024, 10:48:32 pm
I get people looking for it in my eyes a lot as one of the similar-to-my syndromes has it as a key symptom (I don't have it, I have other freaky eye stuff instead).
Post by: FifeingEejit on 11 March, 2024, 11:21:00 pm
Sent from my IV2201 using Tapatalk
Post by: fruitcake on 21 April, 2024, 10:35:49 am
https://www.optometrytimes.com/view/poor-mans-redgreen-test
Post by: hellymedic on 22 April, 2024, 02:15:24 pm
I bought specs with circular lenses and tuned the axis for correction by looking at the red and green lights on my hi-fi...
Post by: Kim on 22 April, 2024, 02:29:02 pm
https://www.optometrytimes.com/view/poor-mans-redgreen-test
I'd wondered about this...
Quote
Blue and red wavelengths are the furthest apart dioptrically with longitudinal chromatic aberration. Why do we use red and green for the duochrome test instead of logically using red and blue?
First, blue light is inherently darker in comparison to green light; therefore, the color green is interpreted as “brighter” than blue by most patients.2 If blue were used for the duochrome test, interpretation of the test may be difficult because some patients might inadvertently choose which side is brighter instead of which side is clearer.
Presumably the red and the green used for the duochrome test are balanced so that they appear to be of equivalent brightness to you trichromats? I find some effort is required to judge the clarity of the red part, because it's so much darker. It sounds like I'd be better off with blue rather than green...