Objective, Repeatable Parallax Test?

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Objective, Repeatable Parallax Test?

Post by DeweyHales on 9/12/2017, 6:20 pm

I'd like suggestions for how to effectively measure parallax in optics typically used for bullseye. I've found an Aimpoint H1 that just won't allow me to shoot a group. This has made me want to test them all.
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Re: Objective, Repeatable Parallax Test?

Post by Multiracer on 9/12/2017, 6:42 pm

Interesting.........I shall await the answers.

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Re: Objective, Repeatable Parallax Test?

Post by LenV on 9/12/2017, 7:23 pm

It is a question that has come up before. I find this to be a great answer.

http://bullseyepistol.com/dotsight.htm
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Re: Objective, Repeatable Parallax Test?

Post by DeweyHales on 9/12/2017, 10:28 pm

For this Aimpoint, you do not have to be near the edge of the tube for big movements.
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Re: Objective, Repeatable Parallax Test?

Post by Saladman on 9/12/2017, 10:38 pm

This may be the most thorough independent test of several commonly available optics.  The report is around 80 pages long and goes into a good level of detail.  It also seems to be pretty well formatted.  Apparently, we should all be using Eotechs...

What is oddly relevant is that the originator of the test was having consistent issues with Aimpoint T1 style optics.  So much so that he banned them from a specific class that he taught due to inconsistent parallax shift.  Perhaps Bullseye shooters 

https://www.ar15.com/forums/ar-15/Red-Dot-Parallax-Test-Results/18-714950/

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Re: Objective, Repeatable Parallax Test?

Post by SteveT on 9/13/2017, 10:53 am

It's not scientific or completely repeatable, but I've rested the gun on a sandbag on top of my shooting box so it stays in the same position and moved my head around to see the effect of parallax.
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Re: Objective, Repeatable Parallax Test?

Post by 1joel1 on 9/13/2017, 10:57 am

The effects of parallax are for closer objects. By the time you get to 25 yards and certainly 50 yards, the better quality red dots will have a negligible amount of parallax. At least, that's what I have noticed with mine.

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Re: Objective, Repeatable Parallax Test?

Post by Aprilian on 9/13/2017, 11:07 am

There is a missing element in that linked study and I wonder if this group has any insight into it (because of the eye professionals on the forum).  That test did not identify which of the testers wore prescription glasses and whether those were the testers whose results fell outside the averages.  It would have then been interesting to know if strength of the vision correction correlated with larger movement of dot.

I can take my single lens glasses and move my head left to right and get the following results when looking at a traffic light (or a multicolored neon sign).   I can move my head and the outline of the traffic light moves slightly - but the illuminated red light moves more allowing it to seem like the two objects are at different focal distances.   When I check my Ultradots for parallax, I know that my glasses form part of the problem.  That requires me to be much more repeatable with my head location, and dot location in the tube, than if (perhaps) I didn't wear glasses.  With a local neon sign (blue and red), I can get the blue part to move significantly farther than the red part.   Hopefully that means a red dot is less affected than other wavelength colors would be.
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Re: Objective, Repeatable Parallax Test?

Post by dronning on 9/13/2017, 11:44 am

I've informally checked parallax on several dots when using the ransom rest @ 50yds.  When setting up the RR so the dot is on my target mark - a 1/2" sticker I always make certain the dot is centered in the optic.  Once everything is set I move my head so the dot is near the side of the optics tube right/left,up/down to see how far off my target mark it is.  The movement has never been enough to concern me, but I will say some of my UD's are better than other UD's.  I'll be at the range tomorrow so I will check my Aimpoint H1 and another Matchdot II.
- Dave
FYI, I don't wear glasses
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Re: Objective, Repeatable Parallax Test?

Post by Chris Miceli on 9/13/2017, 2:46 pm

dronning wrote:I've informally checked parallax on several dots when using the ransom rest @ 50yds.  When setting up the RR so the dot is on my target mark - a 1/2" sticker I always make certain the dot is centered in the optic.  Once everything is set I move my head so the dot is near the side of the optics tube right/left,up/down to see how far off my target mark it is.  The movement has never been enough to concern me, but I will say some of my UD's are better than other UD's.  I'll be at the range tomorrow so I will check my Aimpoint H1 and another Matchdot II.
- Dave
FYI, I don't wear glasses
I heard somewhere that at worst the parallax is 2x the MOA of your dot
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Re: Objective, Repeatable Parallax Test?

Post by blindshooter on 9/14/2017, 6:35 am

Aprilian, I am myopic, around -7 in both eyes and experience the color shift you describe. The red light will move completely off the body do the stop light. I have always wondered how it affects sight picture under different conditions. I managed to make HM and DM with the rifle but the pistol is a whole nother ballgame.

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Re: Objective, Repeatable Parallax Test?

Post by Ed Hall on 9/14/2017, 12:52 pm

To add some credence to the corrective lens movement described above, if you place an iris on your lens, it will often minimize the shift...

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