AR15.Com Archives
 Parrallax on an Eotech?
AR4U  [Member]
8/19/2004 4:36:40 PM
I just bought a used eothech sight off the equipment exchange, and it appears to function normally. However, if I set the sight (by itself), flat on a table and move my head around it, the point of aim changes. I tried this because my groups at 100yrds were huge, although I can still efficiently recycle soda cans at short range. Does anyone else have this problem? I thought the benifit of the holographic sight was that the point of aim isn't dependant on your viewing angle.
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Forest  [Team Member]
8/19/2004 4:44:14 PM
At 100y the EOTech has effective no parallax providing you can see the entire reticule.
SWFA  [Industry Partner]
8/24/2004 12:24:36 PM
EOTech and Aimpoint both claim to be parallax free because they have no magnification. Truth is, all sights regardless of power will have parallax. EOTech and Aimpoint sights have such a minor parallax that it is almot not measurable. The maximum parallax for the EOTech is 1" and it only occurs from the muzzle of the weapon to 25 feet, after that the sight has zero parallax.
Timanator  [Member]
8/24/2004 2:43:12 PM
all you gotta do is put the sight ona talbe, and turn it on and look at an object while move your point of view from side to side of the scope.


There is a bit on both, but not enough to miss at close ranges.
AR4U  [Member]
8/27/2004 4:35:51 PM
With all due respect forest, I know that Eotech claims no parrallax. However, my scope clearly has parralax, as I stated in my first post. I'm going to assume this means its defective and send it back...
Forest  [Team Member]
8/27/2004 5:22:40 PM

Originally Posted By AR4U:
With all due respect forest, I know that Eotech claims no parrallax.


Not only claims it but I have proven it. See my old posting on the subject...

But you haven't proved didly. Putting a sight on a table and moving your head around isn't a valid test. It's too easy to screw up.

Put the sight on a weapon then do a proper parralax test. Fire a group with the reticule centered. Then fire a group with the reticule in each corner.

If there is no parrallax you should have one group in the center (as I did). If you have a problem then you'll have a minium of 3 groups - up to 5.

BTW I ran this test twice. One time where I could see the ENTIRE reticule as I shot (meaning the edge of the circle was in the corner, and another time when the center dot was in the corner (so 1/4 of the circle wasn't visible).

I found as long as you can see the ENTIRE reticule there was no parallax. If you could only see the dot then there was some parallax in the horizontal plane only (none in the verticle plane). Somebody might have links to my old test where I posted the photos of the targets.
DOA  [Team Member]
8/27/2004 7:34:45 PM
Someone on this board asked EOtech this very question and Eotech responce was that the Eotech is parallax free at 50yds and further. Aimpoint is about the same. I'll have to do a search for the thread but it was the Aimpoint VS EOtech thread.
Forest is absolutely correct in that you cannot judge parallax from putting the optic on a flat surface and moving your head around. The sight is designed so you can move your head around and as long as their is a clear view of the reticle, it will hit point of aim where the dot is.
AR4U, if you can hit cans accurately at short range with the EOtech but your groups get larger at 100yards, then IT IS YOUR SHOOTING, NOT THE EOtech.
This is not a flame, just telling you the truth.

Yojimbo  [Team Member]
8/27/2004 9:11:26 PM

Originally Posted By DOA:
Someone on this board asked EOtech this very question and Eotech responce was that the Eotech is parallax free at 50yds and further. Aimpoint is about the same. I'll have to do a search for the thread but it was the Aimpoint VS EOtech thread.
Forest is absolutely correct in that you cannot judge parallax from putting the optic on a flat surface and moving your head around. The sight is designed so you can move your head around and as long as their is a clear view of the reticle, it will hit point of aim where the dot is.
AR4U, if you can hit cans accurately at short range with the EOtech but your groups get larger at 100yards, then IT IS YOUR SHOOTING, NOT THE EOtech.
This is not a flame, just telling you the truth.




That be me!

BTW, SWFA is right you can't make a sight that's 100% parallax free at all distances. All sights have some type of parallex error depending on how they are calibrated.

Here's what EOTech told me.

Subject: RE: Tech support question - Parallax issues with 550 series.


Chris,
I don't belong to the chat group. I do not know how to reply to the group. You can pass along the information:

What I read in the chat was someone looking across the room for parallax. At this close distance you will notice parallax.

The sights do have parallax error of +/- 1.2 " or +/- 0.6" (1.2 " side to side). The sight is designed to be parallax free at long distance 100yds to infinity. At close range, there will be a parallax error equaling to the width of the window which is 33mm or 1.3". A perfectly aligned sight will have parallax error of 1.3" at 10 yds and at 17 ft.

As you move further away from 10 to 40 yards parallax becomes less and is almost zero at 50 yards.

If the sight is parallax free at 10 yds or 17 ft, it would be way out of alignment.

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