Red Dot Optics - Astigmatism & Parallax

[wally0206]

Have some questions about Red Dot optics and individuals with Astigmatism, if anyone is able to share you opinion and experiences.

 

If you wear corrective lens ( Contacts or Glasses) for Astigmatism, and you look thru a  parallax free red dot optics (not holographic etched style) do you still see minor Parallax?

 

I have been reviewing a few different brands and models of red dots , Aimpoint (T2, comp5), Trijicon (RMR), Holosun (503), C-more (Rts), as well as holographic Eotech.

As i have looked at each with corrective contacts both eyes open , or rotate one open and one closed,with a target set at 10 yards and i see some minor parallax in the Trijicon, Holosun and a lot in the Cmore, but I don't think i can see any in the T2 or comp5, or any of the eotech as i assume this is do to design begin different ( not sure if this is correct).

 

I have also tried with my glasses and get the same results, and with no corrective lens my vision is too poor to be able to tell.

Also tried the cell phone method to look thru the sight, and although i don't think i see no parallax on any of the sights aside the cmore, not sure if this is accurate or not.

 

Is it possible for astigmatism to create parallax or is it possible the Trijicon and Holosun specific units i tried have a defect creating the parallax?

 

Appreciate any feedback you may be able to share

[moparnut88]

I use a trijicon and have not noticed anything detrimental. I shoot both eyes open.

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[Janskis]

Just tested with a C-more slide ride. When I moved so that the dot went between the top and bottom of the glass, it shifted approx 2cm @ 3 metres.

 

With and without glasses, wife also saw the same effect.

 

I have yet to see a 100% perfect parallax-free sight. All the red dots I have ever used have had some parallax error. Maybe I have super bad eyes or smth? 

[HalRex]

When I built my first AR I put a 1MOA Holosun dot on it. When sighting a target 100 yds out I would see a cluster of dots rather than a single dot. I had lasik surgery about 15 years ago to correct astigmatism and have been told by others that is the reason for the cluster effect. I replaced the dot with a Vortex Strike Eagle 1 X 6 and am very happy with it.

[Greengun]

Astigmatism or not, I believe not many red dot sight are truly parallax free. Holographic sights such as EOTech should produce less (but not none) aberration than red dots. Prismatic optics with with an adjustable ocular diopter would be the best solution for astigmatism distortion but it’s not a both eyes open system. Based on all the feedback I’ve seen from people with astigmatism, individual results vary differently so when one sees better on a particular red dot it doesn’t mean the experience would be same for you unfortunately.

[zzt]

Astigmatism cannot cause parallax.  If your shooting glasses are corrected for astigmatism, the dot will appear round.  I have yet to look through a red dot sight that was parallax free.  Some are better than others (by a lot ).

[jkrispies]

I'm not sure that we're using the term "parallax" correctly here.  I think the discussion has more to do with glass clarity, dot crispness, and potential magnification within the lenses.  Assuming we're talking about clarity and/or dot crispness:

 

1.  Look at the dot and memorize the abnormality (ie, the dot flares to 3 o'clock) 

2.  Rotate the dot and take note of the abnormality (ie, the dot now flares to 6 o'clock, or it is still flaring to 3 o'clock)

 

If the abnormality rotates with the dot, then the issue is in the optic.  If the abnormality stays consistent despite rotating the dot, then the issue is in your eyes.

 

All optics will have some imperfections.  I've noted variations in dots within the same model, with one being very clear or having a bright dot and the next... not so clear, or maybe the dot just won't crank up as bright as the other one.  This issue is not limited to a single manufacturer either, and it's not limited to cheap vs. expensive either-- remember that these optics are being mass produced by masses of people, using mass produced parts that were created by masses of people, and so forth.  Variation is inevitable despite the best efforts of QC.  I know it's not possible, but if I had my druthers when buying optics, I'd go to a store, ask them to open every box they had of the model I wanted, and I'd go test outdoors in daylight to take the pick of the litter.

 

Lastly, be careful when comparing optics "side-by-side" because they are designed to be viewed through the center of the lens.  if side-by-side, you'll likely have one properly mounted and viewed while the other is "held just right" which gives it an unfair disadvantage.  I've found that RTS2's have excellent glass (with variations!) and if you're saying that you found the RTS2 to have the worst "parallax" then I'd be curious to know if you viewed it mounted on a gun and turned on to ensure you were looking through the center of the lens, or were you just holding it in your hand and looking through it without as much care as if it were in actual use-- no insult here, just curious.  To give an example of what I mean about the importance of viewing it as if in use, it's been my experience that RMR's have clear glass and are true 1x, but the RMR has thick glass, and if you don't look through it straight on, you'll get a coke-bottle effect that results in magnification and distortion.  Looked straight through, though, and the RMR is generally a winner.  This is probably why an optic like the T-1 has an advantage over a projection type dot like the RMR-- due to the limited possibility of angle created by the tube design, it's really difficult to look through a T-1 wrong, whereas I can come at an RMR, RTS2, etc., way off from the side and claim that it's got bad glass when the reality is that I was using it improperly.

Edited June 20, 2018 by jkrispies

[Wisemenofgotham]

On 6/18/2018 at 11:06 AM, HalRex said:

When I built my first AR I put a 1MOA Holosun dot on it. When sighting a target 100 yds out I would see a cluster of dots rather than a single dot. I had lasik surgery about 15 years ago to correct astigmatism and have been told by others that is the reason for the cluster effect. I replaced the dot with a Vortex Strike Eagle 1 X 6 and am very happy with it.

 

This is my situation as well.  I had Lasik surgery and now use a LVPO instead of a red dot on my AR and I love it.  I’ve have Trijicon RMR optics milled onto firearms and I’ve used the ROMEO1, I just try to the best of my ability, even though I do not see a sharp dot.  Howver, I do like the Aimpoint T2 for a rifle, but prefer the 1-6x options better.

Edited June 20, 2018 by Wisemenofgotham

[jkrispies]

Just posted this in a different theead but thought it was apropos here as well:

 

I just got a new RMR (literally, it came in the mail today) and was playing with it varying my focus between the target and the dot, and I can totally see how somebody would think it’s a piece of junk if they weren’t trained on how to use it correctly.  If used properly, though, the dot is crisp and it’s a perfect 1x.  The key is to focus on the target and aim through the glass so the dot superimposes on the target.  Do that and it works perfectly.  Stare at the dot, though, and everything goes wonky. 

[Greengun]

One key issue OP trying to address is astigmatism. When that’s the issue, sadly, it doesn’t matter how clear or crisp the glass is. I have 5 different red dots and for me I can say that smaller dots tend to have tails than bigger dots. And triangle dots work better than round dots.

[GeneBray]

Have some questions about Red Dot optics and individuals with Astigmatism, if anyone is able to share you opinion and experiences.
 
If you wear corrective lens ( Contacts or Glasses) for Astigmatism, and you look thru a  parallax free red dot optics (not holographic etched style) do you still see minor Parallax?
 
I have been reviewing a few different brands and models of red dots , Aimpoint (T2, comp5), Trijicon (RMR), Holosun (503), C-more (Rts), as well as holographic Eotech.
As i have looked at each with corrective contacts both eyes open , or rotate one open and one closed,with a target set at 10 yards and i see some minor parallax in the Trijicon, Holosun and a lot in the Cmore, but I don't think i can see any in the T2 or comp5, or any of the eotech as i assume this is do to design begin different ( not sure if this is correct).
 
I have also tried with my glasses and get the same results, and with no corrective lens my vision is too poor to be able to tell.
Also tried the cell phone method to look thru the sight, and although i don't think i see no parallax on any of the sights aside the cmore, not sure if this is accurate or not.
 
Is it possible for astigmatism to create parallax or is it possible the Trijicon and Holosun specific units i tried have a defect creating the parallax?
 
Appreciate any feedback you may be able to share

Working to find a solution. I don’t think the problem is parallax. When you shoot a rifle the head typically moves in two directions to get proper sight/eye alignment. The head leans to the right. (I am assuming a right handed shooter. If you are a lefty then just reverse things.). Additionally, there is a small among of turning the head to the right. The sum of the movements is the eye and the lens are no longer in the proper relationship to correct the visual acuity problems we experience and distortion to the eye is increased. If you can cant the head without any turning the eye/lens and sight should be properly aligned and things relative sharp. With a red dot the dot (for me) is not sharp. I can live with that. My issue is iron sight and telescopic. Another possible issue can be proper focus distance.


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[moparnut88]

One key issue OP trying to address is astigmatism. When that’s the issue, sadly, it doesn’t matter how clear or crisp the glass is. I have 5 different red dots and for me I can say that smaller dots tend to have tails than bigger dots. And triangle dots work better than round dots.

That's a good point. Both of my delta points are 7.5 moa triangles. And I don't really notice anything but smaller round dots do get weird.

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[yigal]

https://www.breachbangclear.com/parallax-free-isnt/

all colimator sights have paralax. some have less, but it still exist.

[jkrispies]

1 hour ago, yigal said:

https://www.breachbangclear.com/parallax-free-isnt/

all colimator sights have paralax. some have less, but it still exist.

Great article... but video unavailable!  I want to see the results!!!!

[wally0206]

Appreciate all the feedback and different point of views, i see the conversation has a couple different points of view,

 

Most all Red dot optics have some parallax , even if it is very very minor. (and some have a lot)

Astigmatism in most cases without corrective lens can cause the red dot to be distorted , lose shape and or clarity etc.

 

Do some with astigmatism wearing corrective lens still see the red dot being distorted? i myself wear either contacts or glasses to correct my astigmatism, but i don't see any red dot distortion when i wear my corrective lens, it is a normal red dot at all angles, naturally without corrective lens it is a hot mess. With all the feedback and posted links so far, i am still unsure thou if a person with astigmatism wearing corrective lens would see parallax on what is consider a parallax free optic.

 

so maybe the better question is....

 

Hypothetically ,

Does a person with astigmatism that is wearing corrective lens (for 20/20 vision) see more parallax then a person that doesn't have astigmatism (with 20/20 vision) using the same red dot optic, sight \ eye alignment , focal distance etc. ? or would both see the same amount of parallax?

 

[yigal]

if u shoot  fast  ipsc in open div. u don't have time to see the shape of the dot during the drill.

 

[jkrispies]

I don’t believe that parallax would be affected by corrective lenses.   I wear prescription glasses and don’t have an issue myself at all.  I could see how somebody might theorize it creating a problem because you’re basically stacking lenses on top of lenses which introduces an additional variable for error but I’d think that if this were the case it would have been complained about a lot by now given the number of shooters who wear prescription glasses.  Remember also that everyone wears safety glasses while shooting which is still a form of lens so they would complain too.   The most important way to defeat parallax is proper eye to optic alignment, after which any paralax that remains is too minimal to matter.  

 

It might help too if I pointed out that I’ve conversed with optic companies in the past (don’t remember who now but probably Aimpoint or Eotech, and likely C-More) and as I recall they said that the amount of parallax shift they measured was so minor it was irrelevant after also taking into account typical rifle and ammo accuracy variations plus the width of the bullet itself, etc. that also plays into a shot. The parallax introduced something like a possible inch variation at 75 yards with worst use.  Basically it would matter if you’re shooting bullseye, and nobody who shoots bullseye would use this type of sight.  So, when they say “parallax free”, they should really use the term “parallax irrelevant.” 

Edited June 21, 2018 by jkrispies

[jkrispies]

I suspect that my phrase “parallax irrelevant” and inference that a 1” shift at 75 yards is acceptable will raise some ire, so here are a few numbers to clarify my thought process, and the reader can make up his/her own mind from there:

 

Let’s assume a worst case scenario that a red dot has a 1” parallax shift at 50 yards, measured radially, giving a potential 2” diameter of error at 50 yards.  We’ll also assume that the gun it is mounted on shoots 2” groups at 50 yards, or 1” measured radially.

 

Using these numbers and applying a worst case scenario (ie, worst potential parallax error compounded with the worst possible group involving all rounds flying to their extremes in all directions), this would combine to create a potential 4” group at 50 yards.

 

Now… if you’re shooting an 8moa dot (as I do) then the dot would still entirely cover this group at 50 yards, which means that even considering this worst case scenario, the dot still put the bullets exactly where the dot told the bullets to go.  Given the fact that it is unlikely I will shoot my current dot-mounted guns farther than 50 yards—my current shots max out at 35 yards—in my mind we have a “parallax irrelevant” situation.

 

If after reading the above a shooter still find this amount of parallax to be unacceptable, probably due to varying shot distances combo’ed with different dot sizes, then said shooter can apply the same thought process to decide if a dot is right fior him while considering his own variables.  Some shooters will do the math and be happier with a lightly magnified or prism-type scope than a red dot.

[yigal]

the problem not on 50 y.

the big problem is  at close range. under 10y.

[jkrispies]

50 minutes ago, yigal said:

the problem not on 50 y.

the big problem is  at close range. under 10y.

Please explain why this would be a big problem?   

[yigal]

take your  red dot sight and place it on stable rest .

put   apple  5 y. before the sight. look thru the sight .now u  can see the size of the deviation of your sight.

[jkrispies]

55 minutes ago, yigal said:

take your  red dot sight and place it on stable rest .

put   apple  5 y. before the sight. look thru the sight .now u  can see the size of the deviation of your sight.

Yeah, I still don’t get it.  Are you talking about a deviation in magnification?  

[jkrispies]

7 hours ago, yigal said:

take your  red dot sight and place it on stable rest .

put   apple  5 y. before the sight. look thru the sight .now u  can see the size of the deviation of your sight.

So I just put a 1/4” square piece of tape 5 yards in front of a solid mounted Trijicon RMR RM06 Type 2 and did a parallax test.  Aimed at the center of the tape with the dot in the center of the lens (the dot was about the same size as the tape), and I moved my head to circle the reticle around the entire perimeter of the lens. Yes, the dot moved some (evidence of parallax) especially in the horizontal but it never fell off the tape, so you’re talking less than a quarter of an inch possible parallax shift at 5 yards.   I did the same test with an RTS2, and I’m not sure that it moved at all. 

 

The tape target was too small to film, so with the cooperation of an RTS2, by popular demand...

 

Edited June 22, 2018 by jkrispies

[yigal]

probably u have very good designed collimator sights. 

with my aimpoint  it possible to miss the target at this range , the dot moves  more than 2".

with old military meprolight sight it's even worse.

[jkrispies]

1 hour ago, yigal said:

probably u have very good designed collimator sights. 

with my aimpoint  it possible to miss the target at this range , the dot moves  more than 2".

with old military meprolight sight it's even worse.

Possibly!  If I had an old Aimpoint to test I would, just out of curiosity.  If you’re looking for an optic on a game gun, the RTS2 is hard to beat— just don’t drop it.  If you’re running an Aimpoint because it’s on a working gun that will get banged around, I think the RMR Type 2 is as good as you can get for that situation, but that’s only this guy’s opinion.  I just bought one from Big Tex Outdoors and am very happy with both the optic and the vendor.  

Edited June 22, 2018 by jkrispies