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Author Topic: Eyeglass question & color  (Read 4298 times)

walter.sk

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Eyeglass question & color
« on: September 16, 2010, 09:57:35 pm »

I should probably have posted this on an opticians' website but, since color vision is so important to me as a photographer I am asking this here, hoping that somebody has an answer.

I just got new glasses, with high-index lenses, and for the first time in my long life, progressive lenses rather than bifocals.  I do lots of photography and post work on the computer, and I seem to have adjusted quickly to the progressives.  Now, I can actually *read* the text on my NEC 3090, which is more than 2 feet across my desk.

The problem comes when I look at images projected on a screen, and also when I drive.  There seems to be a color fringing effect.  For example, when I look straight ahead but shift my eyes up toward the top of the lenses, the tops of trees far down the road seem to have a red/yellow fringe on the tops.  Looking at the screen with projected images, I also notice some color fringing that goes away if I move my head up or down a bit.  All of this stinks, because I have to see accurate colors.

Are these problems because of the progressive aspect of the lenses, or of the nature of the high index glass (plastic, I guess)?  Or did I just end up with some poorly designed/ground lenses?
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digitaldog

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Re: Eyeglass question & color
« Reply #1 on: September 16, 2010, 10:16:41 pm »

I ended up just having a set made for computer work, no bifocal/progressives. One reason was neither prescription was ideal. I do have to take them off to do other tasks, but for long hours at the computer, they are ideal.
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Johnny_Johnson

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Re: Eyeglass question & color
« Reply #2 on: September 17, 2010, 01:10:39 am »

Are these problems because of the progressive aspect of the lenses, or of the nature of the high index glass (plastic, I guess)?  Or did I just end up with some poorly designed/ground lenses?

I don't have the answer but I've been wearing progressives for at least 15 years and have never noticed any color fringing.

Later,
Johnny
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Bart_van_der_Wolf

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Re: Eyeglass question & color
« Reply #3 on: September 17, 2010, 05:39:34 am »

Are these problems because of the progressive aspect of the lenses, or of the nature of the high index glass (plastic, I guess)?

It's normal "dispersion". I've had it with and without progressives, due to the high refractive index and dispersion trade-off connected with single lens optical materials. Depending on the specific materials, I think there can be an improvement with Carl Zeiss "i.Scription®" lenses (higher order aberration correction) but not all eyes are suited for that approach.

Cheers,
Bart
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Ernst Dinkla

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Re: Eyeglass question & color
« Reply #4 on: September 17, 2010, 06:52:23 am »

I ended up just having a set made for computer work, no bifocal/progressives. One reason was neither prescription was ideal. I do have to take them off to do other tasks, but for long hours at the computer, they are ideal.

I needed -4.5 normally but had some glasses made at -3.5 for monitor distance when old age set in. I use them for all other tasks indoors. I think my eyes adapted more and more to that prescription that I now only need the normal glasses when driving at night. In my experience it is more comfortable when in front of a larger monitor and checking designs, not just for the color shifts.


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Ken Bennett

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Re: Eyeglass question & color
« Reply #5 on: September 17, 2010, 07:36:49 am »

I just got new glasses this summer, and have the same issue of color fringing off-axis. These are single-prescription, not progressive or bifocal. I assumed it was from the anti-reflection coating, since this is the first time I've had that on my glasses.
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walter.sk

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Re: Eyeglass question & color
« Reply #6 on: September 17, 2010, 10:04:16 am »

Thanks for all the replies.  I did some Wiki searches last night and found that CA is quite common with high index lenses.  I think I will go back to my opthamoligist/optometrist office and get their opinion on whether my prescription (very farsighted and astigmatic) would yield less CA on the several types of "glass" available.

I know that my previous pair of glasses were on thicker and heavier "glass" but had no CA that I could see.  I also think I will take Andrew's suggestion, as well as some others, and get a separate prescription for the computer work.

The most disturbing aspect of the nature of the CA with these lenses is not the obvious off-axis fringing that makes the tips of trees look orange, but the thin and very believable contrasting lines that separate solid fields of color that in geometric images would not cue me to move my head to get rid of them.

Boy, getting older has some glitches!
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Bob Smith

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Re: Eyeglass question & color
« Reply #7 on: September 17, 2010, 10:55:38 am »

Correction for astigmatism can induce or minimize color fringing.  I've had an astigmatism correction for years and this became very noticeable with the last annual "tuning" of my prescription.  I'd have really good opthamologist double check your prescription before investing in different glass for your lenses.

Bob Smith
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