parallax ?

John,

I take your point, but I believe when you align the sights of your gun with a target, the misalignment is more dominant eye and binocular vision due to the spread between your eyes.

Generally you are using only one eye in an optical system to achieve alignment between close and infinity. Parallax will kill you at infinity when one must plunge and rotate to start adjusting the mechanical axis of a system to the optical axis.

In any event, the error is there and can be a significant source of error if shooting for groups or not so much if shooting a large target with some variation allowed for shot placement.

The farther away the target, the more significant the error.

When you must consider the wind and mirage, anything you can do to reduce the other variables is helpful.

Geetarman:D
 
...misalignment is more dominant eye and binocular vision due to the spread between your eyes.
Click to expand...
I agree that it's a little strange to think about changing one's observation point by using the weak eye vs the dominant eye (the dominant eye view is what we normally see with both eyes open), but that's what's happening, and that's why it fits the general definition of parallax.
Generally you are using only one eye in an optical system to achieve alignment between close and infinity.
Click to expand...
That's correct, and when talking about parallax involving a typical optic, the change in position is much more straightforward, it actually involves moving the observing eye around relative to the optic.

It can be a significant source of error on the target, depending on a number of variables.
...that most shooters should care and/or understand parallax which is simply untrue.
Click to expand...
At the very least they should understand that it exists and that it's the reason why a consistent cheekweld/head position is important.
 
Parallax as I understand it has to do with the Reticle and Target Focal Planes. When they are on the same plane then there is no parallax. Distance effects parallax. That is why you see yardage increments on the objectives of scopes with adjustable objectives
 
That is true.

It is also true that if your eye is well centered along the optical axis there is no apparent parallax. It makes no difference in that scenario whether or not the target and crosshair are in plane.

That is one of the reasons cheek weld is important.

It is all about variable reduction. Some contribute more and some less to inaccuracy.

Your type of shooting is what determines which of the variables is most important to you.

Geetarman:D
 
I agree with bart. You can talk all kinds of technical mumble jumble but what your really doing is focusing your scope for the range your shooting at.
Close, but not quite right.

Adjusting the objective lens only focuses the target image in the reticule plane. It does not technically correct for parallax because any object closer or further than the target will have parallax on the reticule.

Once the objective lens focuses the target on the reticule, you can move your eye all over the place and there won't be any parallax for anything at that range.
Click to expand...
 
Big Pard mentions:
Distance effects parallax. That is why you see yardage increments on the objectives of scopes with adjustable objectives.
Click to expand...
True, but only if the objective lens is correctly mounted in the objective barrel that focusing moves. I've checked out several scopes over the last several years and half of them (some high dollar ones) have parallax. A few have focused at infinity when their adjustment was set to 100 or 200 yards and some parallax was present. Worst ones were two Nightforce scopes they shipped to me several years ago just to check them out on my bench collimator. Their ajustments were also off by about 7%; moving both E and W turrets to change 10 MOA they actually changed only 9.3 MOA. Both had parallax issues focused at 100 and 200 yards with targets exactly at that distance. I've no idea if they're any better now.
 
You must log in or register to reply here.
Back
Top