Need help figuring out how Eotech work....please advise.... [Archive] - Glock Talk


View Full Version : Need help figuring out how Eotech work....please advise....

Agent Tikki
07-23-2011, 11:51
I had the opportunity to handle an Eotech XPS2.0.

When I put this Sights down on the table.....look through the glass, and move my head to the left and right....the reticle moves with me.

If the point of aim shifts as my position shift, but the sight does not move...doesn't this make the the sight pretty much....useless?

Please explain my observations and how to counteract this.

I mean...If my head was always in the same position relative to the good check weld on the stock etc...I don't see this as being a problem...but if I shift my firearm around tracking a target eye would not be in the same position and poa and poi would not be the same....right? what's going on?:confused:

08-01-2011, 08:47
Parallax is essentially an optical illusion. Parallax presents itself as the apparent movement of the reticle, in relation to the target, when your eye moves off center of the sight picture (exit pupil) or in more extreme cases it appears as an out of focus image. It indicates that the scope is either out of focus or more specifically the image of the target is not occurring on the same focal plane as the reticle. Maximum parallax occurs when your eye is at the very edge of the sight picture (exit pupil). Even when parallax is adjusted for a designated distance, there is an inadvertent error at other distances. Most brands of scopes that do not have a parallax adjustment are pre-set at the factory to be parallax free at or around 100 yards; rim fire and shotgun scopes are set at or around 50 yards. Most scopes of 11x or more have a parallax adjustment because parallax worsens at higher magnifications. Generally speaking parallax adjustment is not required for hunting situations and is primarily a feature used and desired by target shooters. A 4x hunting scope focused for 150 yards has a maximum error of only 8/10ths of an inch at 500 yards. At short distances, the parallax effect does not affect accuracy. Using the same 4x scope at 100 yards, the maximum error is less than 2/10ths of an inch. It is also good to remember that, as long you are sighting straight through the middle of the scope, or close to it, parallax will have virtually no effect on accuracy in a hunting situation.