Science I need you (red dot related)

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Foxer2373

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Alright so we all know that if you have astigmatism red dots look like a peparoni pizza. I have developed this in recent years but have contacts now that fix this. However something curious I noticed yesterday, I put a red dot (vortex strikefire 2) on my rifle then mounted my 3x Vortex magnifier behind it. I have not used the magnifier in years so did not notice this before.... all of a sudden without my contacts the dot was super crisp I'm talking perfection!!!

How and why would this happen?
Has anyone else noticed this?
Does the same thing happen with other combos?
I would also say anyone who can't correct their astigmatism would this be a red dot solution?

Seriously would love the scientific reason how a magnifier would fix astigmatism???
 
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Foxer2373 said:
Seriously would love the scientific reason how a magnifier would fix stigmatism???
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I read something about this awhile ago...at least my recollection is that it is related. It had to do with making "little" circles with your fore-finger next to your thumb, holding them a little ways away, and then looking through both of them. This was supposed to eliminate the astigmatism effect...or so I recall (highly qualified). Something about eliminating certain light waves or focusing the vision or something like that. I suspect that the magnifier may perform a similar function. Just a wild-ass-guess though. Before I had laser surgery, I don't remember a plain magnifying glass helping nor did I notice it with a plain old low mag scope. I also did not notice red dots looking like any kind of pizza though, so maybe that is just me.
 
It has to do with restricting the light rays entering the eye to those parallel with the light created by the dot (reducing flare), and also reducing the eyes tendency to scan outlying items in the peripheries. Wearing polarized sunglasses will have the same sharpening effect, as will looking at the dot through any small opening. I thought my first RDS was defective, but it turns out I have the same problem Foxer. I'm going to tell the old lady I need an Aimpoint 3X for medical reasons ;)
 
Some science here:
http://www.migunowners.org/forum/showthread.php?292639-Red-dot-sights-and-astigmatism

1. The highly monochromatic light from an LED really emphasizes astigmatic error. You might look at a red LED clock in dim illumination and notice the halos as well.

2. If your astigmatism is very well corrected, it helps. However, there are impediments to that. In glasses, the best optics are at the optical center. When they make glasses for you, they measure your "PD", which stands for inter Pupillary Distance. That puts the optical sweet spot (the optical center) right in front of your pupil. However, that assumes your eye and your head are all looking dead straight ahead. When many shooters get up in the shooting position on a rifle, they are NOT looking through the optical center.

And if you wear progressives, this phenomenon is much worse as you get away from the OC. Very common among those over 40...

3. What lens material? Polycarbonate, which has other wonderful properties, has the worse chromatic aberration, which will make the halos/starbursts worse.

4. How big are your pupils? This varies a lot. Big pupils makes it much worse. Many medications will make your pupils bigger. Is it dim illumination? Yup, that makes your pupils dilate, making the problem appear worse.

5. Are your eyelashes in the way? Some folks have long eyelashes, and it's virtually impossible for them to look through an optic, without looking right through the tangle of long curly eyelashes. Yes, that makes it worse. Similar problem if you have droopy eyelids that start to impinge on the pupil area, ditto if you like to squint when you look through an optic.


hope that clears up some of the mystery.

Yes, I'm an eye doctor and yes I'm a shooter. I know -exactly- what you are going through.

troy
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I have an RDS that has a cross-shaped "dot", and that one doesn't have the cloverleaf that an actual dot would have for me.
 
When I look through my Leupold Deltapoint, I see three little triangles in a tight cluster. Good enough for banging steel out to 50yds or so but if I want to shoot further than that I have to flip up the rear peep sight that will co-witness with it. When I look at the triangle through the peep site it is crisp and bang on.
 
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