Astigmatism - wavelength matters?

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Astigmatism - wavelength matters?

Post by bbmann on 5/30/2017, 10:15 pm

I'm not an eye guy, but based on real-life experiences and a bit of searching articles on the internet it seems that astigmatism varies by the wavelength of the incoming light. What this means to shooters is that different red dots will have different wave lengths and your astigmatism effect will vary with the wave length of the dot. So if a Aimpoint has a nice round dot but an Ultra-Dot doesn't that could just be the difference in the wave-length of the dot light. I've seen a lot of random complaints about red-dots and this might explain why some people see round dots and others don't on various red-dots.

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Re: Astigmatism - wavelength matters?

Post by scrum derringer on 5/30/2017, 10:39 pm

I recently bought a several aimpoints ( 9000sc, PRO, ACO, and a Micro) as well as the new-ish SIG Sauer Romeo5, after switching from ultradots. The micro, and most expensive, has the biggest and only starburst image of them all. Surprisingly, the SIG Romeo5 seems equal or better than the Micro. I do also have astigmatism, which ironically was discovered due to bullseye shooting 5 years ago, after reading that only the front sight should be clear...everything was blurry.
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Re: Astigmatism - wavelength matters?

Post by davekp on 5/31/2017, 6:20 am

All reds will have nearly the same wavelength.

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Re: Astigmatism - wavelength matters?

Post by Froneck on 5/31/2017, 7:40 am

The old red dot scopes didn't have the starburst effect until set near max brilliance. But then again my eyes are getting older. The other day I found an old red dot, kind of beat up from years of shooting and then laying in a junk pile. Put a battery in it and was surprised to see the dot was still as it was when my eyes were younger. I'm wondering if what they did to extend battery life has anything to do with it. From what I understand they are actually blinking at a fast rate now.

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Re: Astigmatism - wavelength matters?

Post by xmastershooter on 5/31/2017, 8:55 am

davekp is correct.  I own 5 Ultradot scopes and the quality of the red dots differ from one another.  The best is the 4-DOT with 4,8,12,16 moa which I have in the 30mm and 1 inch.  The MatchDot 2,4,6,8 moa red dots are not as good, with one scope actually magnifies the target slightly.  Even with the same dot size settings, the dot sizes are different between the 4-DOT and the MatchDot scopes.

The human eye does see wavelengths of different colors in different distances though.  For instance, we see red closer than green.  This may explain why some shooters note the red dot closer than the black bullseye when shooting.  I cannot imagine and I'm not sure the manufacturers designed this with a purpose when one company cannot even resolve the negative magnification problem.

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Re: Astigmatism - wavelength matters?

Post by Magload on 5/31/2017, 8:56 am

I have bad astigmatism to the point where glasses don't 100% correct them.  I have a contact that will but hate to wear it.  With a EyePal on my shooting glasses the dot becomes perfectly round.  Don
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Re: Astigmatism - wavelength matters?

Post by Aprilian on 5/31/2017, 12:37 pm

The problem I can have is due to the correction in my glasses.    I can look at a traffic light (straight on) and the light is centered in the frame.   I then turn my head to alternately look out of each edge of the lens and the light moves left to right moving independent of the frame.    That same thing happens with my red dot, so I try to be careful that it is zeroed at my normal offhand head angle and not two-handed looking through the exact center of my lens.
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On a good day...

Post by bbmann on 5/31/2017, 9:01 pm

On a good day I have no problems and the dots are round. On a bad day they have tails or are doubles. My much older friend who has astigmatism correcting contacts always sees a round dot on my red dots. It's very frustrating. However, he (like me) has a big problem with green lasers. His corrections do him little good with green lasers.

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