parallax

sniperman

hi lads,what does parallax mean in rifle scopes?thanks,

FISMA

sniperman wrote: »

hi lads,what does parallax mean in rifle scopes?thanks,

Parallax, in the context of scopes, is an optical illusion whereby the reticle appears to move with respect to the target. This apparent motion is something that you do not want. Instead, you want the reticle fixed on the target.

With your two hands, make a cross with your index fingers. Extend your arms fully, and use the cross/reticle to cover an object in your room.

Move your head a bit and you will see the object move with respect to the cross/reticle. This apparent relative motion is parallax.

steyrman2

hi have a look at the link below
https://www.google.ie/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&sqi=2&ved=0CDgQFjAB&url=http%3A%2F%2Fwww.6mmbr.com%2Fparallax.html&ei=k7Y3UfGZEoKShgeJsoDYDQ&usg=AFQjCNGc74CS-nW3aZpOqfxnE_2-YKxJ4w&sig2=NhP4A_HRv4eUNyz_VDrjlw

extremetaz

First of all, parallax is pretty much as FISMA described above - it's the apparent movement of one object with respect to another on account of them each lying at different distances from the observer. Think of the difference in apparent movement that you see between trees at the side of the road and mountains in the background as you're driving along.

That link that steyrman provided is a pretty good one but the uuber simple explanation is this:

The target is a certain distance away from you, and lies in what can be referred to as the "target plane".

The reticle is focused a certain distance in front of you in what can be referred to as the reticle "focal plane".

In order for the reticle to remain fixed in place on the target regardless of your head position, then the "focal plane" for the recticle must lie at the same distance as the target plane.


Example:
Hold a piece of paper at arms length and a pencil about half way between it and your face. Move your head and the pencil appears to move with respect to the paper.

Now put the pencil in direct contact with the paper and move your head - no more apparent movement between the two (or very very little if you want to be picky about things).


So - when both the target and the reticle planes lie at the same distance, then the potential for parallax error is eliminated because your head position no longer changes anything (or rather no longer changes anything with regard to how you perceive the reticle on the target).

You can adjust the distance to the focal plane of the reticle by altering the distance between the reticle lense and the front lense of the scope - This is what AO scopes do with the front lense, and SWAT scopes do in the center. "Fixed" scopes don't offer this adjustment as conveniently, but it is still there.