LED light frequency and vision correction.

Icebreak

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I've been trying to figure out how to word this for over a year. I'm hoping this thread takes a bit of a scientific discussion in slant.

I'll go ahead and get the disclaimer/warning out of the way. Be careful with UV and NUV lights.

When I hit the magical 40 yr. old mark my vision went south in a hurry. Not terrible, I just can't read very well without glasses or contacts. I have astigmatism. Distance is kind of blurry for highway signs. Close up for reading is worse.

Well, I was shining a 5W RB across the room at a black and white towel. It appeared to be fuzzy and out of focus. Instinctively, I reached up to see if I had my glasses on. They were. I shined another white 3W at the towel and it appeared to be in focus. I took my glasses off and, as expected, it was out of focus. Then with my glasses still off, I shined the Royal Blue at the towel and is was very much in focus. Huh? Then I shined the Royal Blue at a book shelf and I could read the titles on all the books. It's really an astonishing effect.

Let's take this outside. At night of course, with my glasses on and shining the Royal Blue at foliage, everthing looks way out of focus. Take the glasses off and everything is in focus.

A couple of years back, a rather colorful member (MutineySpears) told us that he was a stage performer and was legally blind. He said he was wearing an antenna he built. On the left antennea was a Red/Orange emitter. On the other antennea was a Royal Blue emitter. He explained that this set up helped his ability to see and navigate significantly. We had a pretty good discussion about it but it wasn't until I saw it for myself that I truly understood what he was talking about.

I was reading a recent thread by Cobb who is legally blind. He notices improved reading ability using white LEDs which are bluer than incandescant lights. If I'm looking through the top of the lenses of my no line glasses (this area is for distance) predictably I can't read fine print text very well. I picked up a seven 5mm blue led light and shined it at the fine print text and it came into focus.

Could it be that many of us that prefer LEDs for detailed work are enjoying some vision correction?

That's not really my question. I'm convinced that higher frequency light improves my vision because I've seen it right before my eyes.

My question is...why?

I have some theories but I would like to know what you guys think.

------------------

- Jeff

***EDITED*** to say higher frequency. Thanks, Jan.
 

Haesslich

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I find the blue lights improve contrast, especially the RB ones, which may be why you were able to read titles on a shelf with that when you couldn't do the same with the 3W white.
 

PhotonWrangler

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Different wavelengths have very slightly different focal points in the retina. I learned this when reading about IR lasers; apparently IR wavelengths focus in front of or behind the retina compared to visible wavelengths.
 

IsaacHayes

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yup it's how the light bends/focuses... Typically people find blue tinted HID car headlights to have a lot of glare more than yellow.

But for me, for somereason, they don't glare near as bad. With glasses I can see perfect, better than most people, and yellow still irritates me. With contacts I have +.5 out of focus due to astigmistism, and the yellow lights have a much larger halo or starburst around them than the bluer lights do. (also contacts will create halos around pin points of light even if you have perfect vision with them).

I tried astigmastism toric contacts, and it gave me a weird double vision ghosting affect in the daytime that made me sick, and made lights halo really bad. A car's tail lights would look like they had 6 of them!!! So I ended up going back to normal contacts as nighttime driving was impossible, and in the daytime I couldn't read small stuff super far away any better because it was sharp but had a ghost image off to the side of everything. I went up to -.25 more on my normal contacts and now see almost perfect.

I'll have to try RB light without contacts/glasses and check it out too.

I think the appeal of the white/bluish LED is BOTH; how the wavelength focuses on your eye (may improve focus for some people) and that the color seems sharper for other reasons. When I see an incandecent I just see dim yellowish stuff, but a white led it seems like I can make out so much more with less light... With yellow incandecnets, grass and trees seem to blend together, but with LED's the colors don't seem so muddy and seem to seperate better because it's not throwing out so much of the same color as the bark/leaves respond to I guess..
 

jtr1962

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I find that things just appear crisper and more natural under whiter light. It's no surprise that they should, either. Vision is based on millions of years of evolution to obtain optimum results under a 5500K source, namely the sun. While the brain has an "auto color balance" of sorts so that we don't get physically ill under other light sources, the fact is that our vision is not at its best unless the light source is around 5500K and has a reasonably full spectrum. I find that things look more blurry to me at sunrise/sunset, under incandescent light, and especially under those awful sodium vapor streetlights.

Depsite their less than full spectrum, I still prefer LEDs over incandescents. I even preferred the old school cool white fluorescents over incandescents. Given a choice, I'd rather have some colors drop out and have a whiter light than have a yellower light source (which makes purples, blues, and greens drop out anyway). Thankfully, with today's fluorescents and tomorrow's better CRI LEDs there is no need to make such a compromise any more. I heard yellower light is better for seeing under fog conditions, but for most conditions, and all indoor lighting, 5500K is optimal.
 

JanCPF

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Jeff,

That's a very interesting observation

[ QUOTE ]
Icebreak said:
I'm convinced that lower frequency light improves my vision because I've seen it right before my eyes.


[/ QUOTE ]
That should be *higher* frequency (shorter wave lenght) right?

[ QUOTE ]
jtr1962 said:
I find that things just appear crisper and more natural under whiter light. It's no surprise that they should, either. Vision is based on millions of years of evolution to obtain optimum results under a 5500K source, namely the sun. While the brain has an "auto color balance" of sorts so that we don't get physically ill under other light sources, the fact is that our vision is not at its best unless the light source is around 5500K and has a reasonably full spectrum. I find that things look more blurry to me at sunrise/sunset, under incandescent light, and especially under those awful sodium vapor streetlights.


[/ QUOTE ]
Very good explenation IMO. It's only logical that the good tinted LED's are better for color rendition, although I know that many will disagree with me and swear by incans. Maybe color rendition is so individual from one person to the next, that CRI numbers are in fact useless. I don't know, but I for one don't look to much at those numbers.

Jan
 

Doug Owen

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I think what we're talking about here is chromatic aberrations, that it light of different colors focuses at a different point as another poster points out. This is different from spherical aberrations, where light through different parts of the lens focuses at different points (simple astigmatism). The effect of both is the same to your eyes, out of focus.

Also in play is depth of field, the difference in distance between the nearest and farthest points in focus. This gets better with more light (regardless of color) since your eyes 'stop down' (get smaller openings) and the center of the lens has better depth of field than the edges. All things being the same more light is better to see (which is why you need more light to read than find the book). Even with 'perfect vision'.

Nothing more than higher light levels makes it better for most of us.

It's also worth noting that the human mind is an amazing device. Our vision is flawed in many ways, including a built in blind spot in each eye where the optic nerve enters we ignore. We adapt to these flaws, those of us who are color blind 'don't know it' for instance. Nor are we confused by two slightly different visions of the world, one from each eye. Look at something in the distance, then hold your thumb out at arm's length and 'cover it up'. You really see two trees and two thumbs, right? One with each eye. But your mind knows there's only one of each, so it lies to you. Doubt it? Try closing one eye at a time. Notice when you close your dominant eye your thumb jumps (but not when you close your weak eye)? BTW, the dominant one is set by genetics, it isn't necessarily the one with the best vision (in fact half the time it's not). You can't always trust what you see with your own eyes.......

When things are marginal, meaning you're having trouble seeing well, any improvement is an improvement. When you see well, such changes in light level or color don't do much because you have sufficient margins.

Doug Owen
 

Icebreak

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Haesslich -

Yes, I notice contrast improvement with white, blue and cyan LEDs with glasses on or off. With blue, cyan and Royal Blue I see focal improvement and I think I see some slight focal improvement with white LEDs.

Also, I may be one of the few that finds cyan to be useful in the woods do to contrast between objects and opposing shades of green and green foliage opposing the gray or brownish gray of the bark on trees, vines and shrubs.

pw -

That's what I thought. Thanks for the confirmation.

IsaacHayes –

Those are some very interesting observations. I've noticed some of them as well.

I turned down bi-focal contacts. I don't know what toric lenses are but I don't think I would like them. I went for an averaged improvement for my contacts. I had one set of glasses made specifically for viewing a monitor with my contacts on. I see best with my no-line, no-rim glasses and no contacts. I like the no rim glasses. They are very light weight.

[ QUOTE ]
IsaacHayes said:
I think the appeal of the white/bluish LED is BOTH; how the wavelength focuses on your eye (may improve focus for some people) and that the color seems sharper for other reasons.

[/ QUOTE ]

I agree completely with this. I would also say that in certain environments (distance with ambient light) traditional light sources work better for me but I don't want to tangent too much. For spotting spiders by the reflection in their eyes or spider webs a 3X3W Tri-Star is amazing.

I would be interested to find out if you experience a similar vision correction phenomenon using a Royal Blue.

Jtr1962 –

Nicely articulated.

I can't stand the sodiums either.

I tried to see what you were talking about with blurriness at sunset just now. I think I get lost in how object's colors jump out. I'll try again. I can't remember if photographers call dawn or dusk the magic hour.

Jan –

Thanks for the correction. I've edited my initial post.

Doug Owen –

I'm glad you joined the discussion.

[ QUOTE ]
Doug Owen said:
I think what we're talking about here is chromatic aberrations, that it light of different colors focuses at a different point as another poster points out. This is different from spherical aberrations, where light through different parts of the lens focuses at different points (simple astigmatism). The effect of both is the same to your eyes, out of focus.


[/ QUOTE ]
Ah! Yes. I understand.

[ QUOTE ]
Doug Owen said:
Also in play is depth of field, the difference in distance between the nearest and farthest points in focus. This gets better with more light (regardless of color) since your eyes 'stop down' (get smaller openings) and the center of the lens has better depth of field than the edges. All things being the same more light is better to see (which is why you need more light to read than find the book). Even with 'perfect vision'.


[/ QUOTE ]
I've understood focal length but never thought about how aperture affects it. Very good.

[ QUOTE ]
Doug Owen said:
When things are marginal, meaning you're having trouble seeing well, any improvement is an improvement. When you see well, such changes in light level or color don't do much because you have sufficient margins.


[/ QUOTE ]
Agreed. That explains the crux of the biscuit. With this I would venture that a person would have to have poor vision to experience the phenomenon. With cyan I see some improvement in focus. With blue I see substantial improvement. With Royal Blue I see a dramatic improvement. It is almost like putting my glasses on.
 

SemiMan

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There is a relatively simple explanation for what is happening. The IRIS in your eye responds predominantly to shorter wavelengths. Hence, when you use White LEDS, or added a bright blue LED to the equation, it causes your IRIS to close. Just like a camera, the more closed the IRIS, the greater the depth of field and hence the higher likelihood that what you were looking at was in focus.

I like using a White LED for reading, or alternately daylight flourescent lamps. Either will cause your eye to close more than the equivalent warm light (i.e. halogen, warm flourescent, etc.) and give you better depth of field and make your eyes work less to focus.

Semiman
 

SemiMan

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There is a relatively simple explanation for what is happening. The IRIS in your eye responds predominantly to shorter wavelengths. Hence, when you use White LEDS, or added a bright blue LED to the equation, it causes your IRIS to close. Just like a camera, the more closed the IRIS, the greater the depth of field and hence the higher likelihood that what you were looking at was in focus.

I like using a White LED for reading, or alternately daylight flourescent lamps. Either will cause your eye to close more than the equivalent warm light (i.e. halogen, warm flourescent, etc.) and give you better depth of field and make your eyes work less to focus.

Semiman
 

SemiMan

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There is a relatively simple explanation for what is happening. The IRIS in your eye responds predominantly to shorter wavelengths. Hence, when you use White LEDS, or added a bright blue LED to the equation, it causes your IRIS to close. Just like a camera, the more closed the IRIS, the greater the depth of field and hence the higher likelihood that what you were looking at was in focus.

I like using a White LED for reading, or alternately daylight flourescent lamps. Either will cause your eye to close more than the equivalent warm light (i.e. halogen, warm flourescent, etc.) and give you better depth of field and make your eyes work less to focus.

Semiman
 

SemiMan

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There is a relatively simple explanation for what is happening. The IRIS in your eye responds predominantly to shorter wavelengths. Hence, when you use White LEDS, or added a bright blue LED to the equation, it causes your IRIS to close. Just like a camera, the more closed the IRIS, the greater the depth of field and hence the higher likelihood that what you were looking at was in focus.

I like using a White LED for reading, or alternately daylight flourescent lamps. Either will cause your eye to close more than the equivalent warm light (i.e. halogen, warm flourescent, etc.) and give you better depth of field and make your eyes work less to focus.

Semiman
 

SemiMan

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There is a relatively simple explanation for what is happening. The IRIS in your eye responds predominantly to shorter wavelengths. Hence, when you use White LEDS, or added a bright blue LED to the equation, it causes your IRIS to close. Just like a camera, the more closed the IRIS, the greater the depth of field and hence the higher likelihood that what you were looking at was in focus.

I like using a White LED for reading, or alternately daylight flourescent lamps. Either will cause your eye to close more than the equivalent warm light (i.e. halogen, warm flourescent, etc.) and give you better depth of field and make your eyes work less to focus.

Semiman
 

Icebreak

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Doug Owen made reference to this and you've added the more reactive response of the iris to lower wave length. That makes since. I know a couple people that really dislike even one 5mm blue LED shining at them from 20 feet away. They say it hurts their eyes. I'm thinking that this is part of what is going on but I also think that PW and and Doug Owen's references to chromatic aberrations is at work too.

In mid day sun the iris is probably at its' smallest and I still need glasses.

I could be wrong.
 

VidPro

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that is what i would want to know from your studies also.
get a mirror /ubbthreads/images/graemlins/smile.gif and look at your pupils for how large the iris is at during each light type.
that would at least provide much more information.

the bluish light, has a tendancy to be the blurriness in my eyes :-( but i am only starting to go blind, it adds the fuzzy feeling to the colors. course it depends on what i am LOOKING at , it seems to reflect off WHITE very well, and adds the fuzziness when outdoors.

outdoors i was thinking , heck organically there aint much BLUE, (george carlin says no blue food) even the blue food out there is violet. so mabey why i get fuzzy from blue light outdoors, is the light isnt reflecting off much.
it DOES reflect off things like the white flowers though.

yet blacklight type colors reflects back from all the white very sharply for me, especially after adapting to the dark.

its cool to go walking, and punch up each color and combos of the different colors, and realize its how the colors are reflected off of WHAT is there. . TO reflect off of.
Dirt is brown, grasses are green and yellow, unless there is blooming or human interventions, there isnt a Hawiian shirt in nature /ubbthreads/images/graemlins/smile.gif

indoors when lighting up a piece of paper, the blue does that well, in fact some "superbright" types of paper, have added blue in them. they are not really white.
same things with various "bluing" and Phospates, and Additives in Laundry chemicals, they add in Blue, to fake that it is whiter lookin.
 

Icebreak

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I don't think I can produce the proper environment to do the experiment safely and accurately.

So blue causes some blurriness for your basically good set of eyes? Interesting.

[ QUOTE ]
VidPro said:
yet blacklight type colors reflects back from all the white very sharply for me, especially after adapting to the dark.

its cool to go walking, and punch up each color and combos of the different colors, and realize its how the colors are reflected off of WHAT is there. . TO reflect off of.
Dirt is brown, grasses are green and yellow, unless there is blooming or human interventions, there isnt a Hawiian shirt in nature /ubbthreads/images/graemlins/smile.gif


[/ QUOTE ]

I enjoy doing that too.
 

HarryN

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Hi Icebreak, I think this was not mentioned above, although I might not have seen it /ubbthreads/images/graemlins/smile.gif Most people's vision reaches its peak at the age of 9, after that, it continuously deteriorates, so that around the age of 40 - 50, it becomes very obvious. Part of this has to do with the decreased flexibility of the lens IIRC.

My 9 year old daughter can easily locate and place a 1 x 0.3mm component exactly where it needs to go (with no optical enhancement). No chance for me.
 

Moat

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I've noticed the same effect at concerts, when the stage was illuminated with alternating solid colors (say, red/blue/green/yellow) - things would appear stunningly clear under one color, and strainingly un-focusable under another. Can't quite recall which, but I think blue was clearest and red the most out-of-focus (for me, wearing glasses).

I assumed it was likely some result of the eye's differing angles of refraction for different wavelengths, playing about the focal point... somewhat like sunlight being "split" (refracting at differing angles) into the colors of a rainbow, via the "lens" of a raindrop - but in reverse... umm, well... something like that...?

So, maybe somebody really smart will invent a contact lens polymer that'll auto-adjust it's thickness/correction to the dominant wavelength... for those of us past 40... /ubbthreads/images/graemlins/tongue.gif
 

Icebreak

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HarryN -

Now I know how you build all those wonderful electronics. /ubbthreads/images/graemlins/wink.gif

Hello, Bob.

Long time no talk.

From what I hear the Mitten is doing pretty well.

Thanks for the account of your experience at the concert. That's a great lab for checking out this phenomenon. I like live music better than any so I'll make sure to check out the effects. I'm thinking I'll experience the same thing you did with blue lights. Every once in a while we'll go dancing at a club that has black lights everywhere. I'm now curious how my vision is there without my glasses on.

I like your invention. Maybe two layers? One shrinks according to dominant light forcing the other layer to reform and refocus. Yes, I thought about it too long.

...if only I were really smart.

------------

- Jeff
 

Moat

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Hi, Jeff.

Yeah... my buds call me "silent Bob". /ubbthreads/images/graemlins/smile.gif

Certainly a very warm, green Mitten the past few days!

The more I attempt to recall, it may indeed have been red the clearest, and blue the most out of focus, instead. (seems my aging powers of recollection are diminishing right along with my eyesight... /ubbthreads/images/graemlins/banghead.gif )

I had the thought that it might be interesting to repeat your "towel illumination experiment" using a red light source - being it's roughly at the opposite end of the visible spectrum from your RB. Then maybe attempt to focus on a nearer object (say, your white-illuminated hand) and notice if the background, peripheral out-of-focus color becomes more in focus (err... again... something like that...?).

Which brings up the question - is it possible the eye/brain references a "preferred", somewhat specific wavelength to focus? Like nearer to red than blue, as (I believe) there's less blue in natural sunlight than red... /ubbthreads/images/graemlins/icon3.gif IOW - it might just be naturally more difficult to focus on blue, vs. red (??). (just a WAG - your post a ways above implies the opposite, for instance)

Although, I'd guess it has more to do with simply making things "clear" (comparing "sharpness" of contrasts) - regardless of color. Your impressions of contrast improvement under bluish light may actually be aiding the ability to focus, then.

Egad - I thought about that too long, TOO!
 
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