Parallax??

shredder

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I've searched the forum and couldn't locate an answer for this question:

What is parallax (when referring to scope optics)?

I always thought it meant the focus.
 
Google = your friend
Parallax is an apparent displacement or difference of orientation of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.[1][2] The term is derived from the Greek παράλλαξις (parallaxis), meaning "alteration". Nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances. In astronomy, parallax is the only direct method by which distances to objects (typically stars) beyond the Solar System can be measured. The Hipparcos satellite has used the technique for over 100,000 nearby stars. This provides the basis for all other distance measurements in astronomy, the cosmic distance ladder. Here, the term "parallax" is the angle or semi-angle of inclination between two sightlines to the star.

Parallax also affects optical instruments such as binoculars, microscopes, and twin-lens reflex cameras which view objects from slightly different angles. Many animals, including humans, have two eyes with overlapping visual fields to use parallax to gain depth perception; this process is known as stereopsis.

Aimpoints and Eotechs along with some others all have this.
 
Scopes don't point at the crosshairs if your eye isn't centred or consistently positioned, except at the distance for which paralex is set. The error isn't huge, but for varying distances and extreme precision, the error is there. Adjustable paralex helps reduce that error.
 
The simple answer is the apparent movement of the crosshairs on target when your eye changes position. Since a scope can only be parallax free at one distance adjustable objectives were developed to compensate. Focus and parallax are different, but adjusting the parallax also changes the focus.
 
Eye relief is the distance you have your face away from the scope or red dot.

Rifle scopes having very little eye relief, red dots (most) having unlimited.
 
Thank you, gentlemen!!!

So from the descriptions of parallax and how it affects accuracy at extreme long ranges, I really shouldn't worry about it if I'm shooting gophers at 50-100 yds or deer at 300?(with different scoped rifles, of course:D)

FYI, the gopher gun is an Anschutz (that I haven't put a scope on yet) and the deer gun is a Remington 700 with a 4x Burris scope (dad's gun he doesn't use anymore, so I get it:p)
 
Thank you, gentlemen!!!

So from the descriptions of parallax and how it affects accuracy at extreme long ranges, I really shouldn't worry about it if I'm shooting gophers at 50-100 yds or deer at 300?(with different scoped rifles, of course:D)

FYI, the gopher gun is an Anschutz (that I haven't put a scope on yet) and the deer gun is a Remington 700 with a 4x Burris scope (dad's gun he doesn't use anymore, so I get it:p)


For 50-100 yard gophers and 300 yard deer you would be better off forgetting about parallax altogether. When you switch it around to 300 yard gophers then it's a different thing. An exception would be if you are running high powered scopes on the Anschutz. I had a 6-24 on my MS gun, which would have been useless without an AO.
 
I used to buy only AO scopes, now I prefer them without. My level of precision shooting doesn't require me to worry about paralax.

BTW, isn't parallax irrelevant if your eye lines up perfectly every time?
 
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I found the AO to be a pain in the ass when shooting gophers. The gophers pop up from 15' to as far as you can see them. If I was going to spend money on another parallax adj scope I would get side focus and see if that's more handy. But for deer, I'd never use one.
 
if looking though the scope with your eye centered you don't need to worry about paralax on a big game scope. most centrefire scopes are set at 100 to 150 yrds. out to three hundred or so i don't want to be fiddling trying to adjust the scope. i rather just point and shoot. field shooting possitions cause more aiming problems than paralax does. also the effect of paralax is more pronounced at 10x or over like in varrment scopes. if you shooting at 4x or 6x power the effect of paralax is negligible.
 
I'm nitpicking here, but parallax does not vary depending on magnification. Only objective diameter, distance and how far off center your eye is works into the equation. What you notice about higher magnification, is that the parallax is more easily observable owing to the magnification - ie smaller movements are magnified- however the aiming error itself is the same as it is on lower power scopes. There might be for instance a maximum parallax error of 1/2" on a scope at a certain distance. You can barely see the 1/2 movement on a 4x scope, and see it quite prominently with a 24x, but its the same potential for error with either scope.

I think the bottom line is that 1/2" errors in point of aim are of no consequence in most field scenarios and would be the least of my worries. There's plenty of other things I can do wrong to miss.
 
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