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Old June 19, 2011, 07:16 PM   #1
weix11
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Riflescope Parallax

Hi, I was wondering whether using a scope that is parallax free at 100 yards would affect accuracy in any way if I shot under 100 yards, like 50-60 yards. How big would the parallax error be if I shot under 100 yards?


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Old June 19, 2011, 07:23 PM   #2
dawico
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There wouldn't be much error, or any at all if you have a consistant cheek weld. If you have your eye in the same place relative to the scope, parallax isn't an issue.
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Old June 20, 2011, 06:16 AM   #3
B.L.E.
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Like dawico said, parallax only comes into play if your eye is not perfectly centered on the scope.

If shooting at targets farther away than the parallax free distance, the point of impact moves the same direction your eye moves off the scope axis.
Shooting at targets closer than the parallax free distance and the point of impact moves opposite the eye movement.
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Old June 20, 2011, 06:21 AM   #4
ZeroJunk
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My problem with it is that if I focus on the target the crosshairs are out of focus and if I focus on the crosshairs the target is out of focus.
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Old June 20, 2011, 06:59 AM   #5
Art Eatman
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If your eyebone is off-center such that parallax is a problem, you might well miss a ground squirrel, or get lousy groups.

ZJ, sounds like your scope isn't properly focussed. You should be able to adjust the eyepiece such that the crosshairs and the target are both sharp.
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Old June 20, 2011, 07:39 AM   #6
geetarman
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On most scopes, focussing the reticle is distinct from focussing on the target.

Normally one runs the eypiece clockwise until the reticle is distinctly out of focus.

Begin turning the eyepiece ccw one or two turns until the reticle comes into focus. The trick is to not stare at the reticle nor to stare at a target.

If possible, stare at a neutral background like a distant mound of dirt or toward the sky.

Mount the rifle and take a quick look. The reticle should pop into focus immediately. If it doesn't, your eye will try to accomodate and the result will be some eyestrain.

Move your head away from the scope and let your eye relax. Continue to mount and dismount the rifle, adjusting the eyepiece as required to achieve a sharp focus on the reticle without staring at a target.

Once that is done, you are good to go as far as the eyepiece is concerned.

If you have either a side focus knob on your scope or a front bell adjustment for target focus, that adjustment is your parallax adjustment.

If you have a target posted at 100 yards, begin adjusting that knob until the target comes into focus and don't move the eyepiece.

As the target comes into clear focus, begin shifting your eye from side to side and check for apparent movement between the target and the reticle. If you see movement, that error is parallax. It is caused by the target and the reticle not being in the same plane.

If you see that sort of movement, continue to adjust the side focus knob or the objective bell until the movement is either gone or it is at a minimum.

Now you should have both the target and your reticle in sharp relief and you are good to go.

One caution, if you are using a fixed power scope, like a Weaver K6, at shorter ranges ( 50 yards and closer ), you may not be able to get a clear image of the target. Don't adjust the eyepiece to try to make the target come into focus.

On a fixed power scope with no parallax adjustment, the scope is nominally set to be parallax free at 100 yards. In that case, adjust the eyepiece as described to be in focus when viewed at a neutral background. If your target is fuzzy, then most likely you are too close to it.

Most adjustable power scopes have both adjustments for reticle and target focus. They are two different adjustments and serve two different purposes.

Hope this helps.

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Old June 20, 2011, 08:57 AM   #7
ZeroJunk
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I was referring to using a parallax free at 100 yards scope on a 22 for squirrel hunting in a 70 or 80 foot tree. You can use an adjustable objective scope and turn it down to say 25 yards and it works great. A fixed at 100 parallax scope doesn't work for me for the reason I explained. You may be able to adjust the eyepiece for this. But then, if you want to shoot a ground hog at 90 yards you are right back in the same boat.
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Old June 20, 2011, 10:56 AM   #8
Poodleshooter
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You shouldn't ever use a reticle focus eyepiece to adjust image focus. It's like chasing rainbows. There are certain distance/magnification combinations that are not possible with certain scopes. That's why when your reticle is out of focus your image is in focus and vice versa. For rear reticle focus rings, set it and forget it.

Keep in mind that an object in focus is not necessarily parallax free,BTW.

Here's an example:
Take a 4-12x scope with fixed 150yd parallax to the range. Turn it down to 4x and the 25yd target is in focus. Now crank it up to 12x at 25yds. The target is now blurry. The maximum parallax error has not changed however!


Short version: If you want to use a centerfire scope at close range, use low power, and keep your eye perfectly centered to avoid parallax.
If you want to avoid parallax problems and move your head around, or if you want to shoot at high magnification and close range, get an AO scope.
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Old June 20, 2011, 12:37 PM   #9
bedlamite
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I've found it's not significant at closer ranges when using a scope focused at 100 yds.

Try it for yourself: Put a scope focused at 100yds on a rifle and get it sighted in at 100 yds. Then shoot a few groups at closer ranges with your eye as far off center as possible.

Trying to get the biggest parallax error possible, the farthest off I could get was about 1/2" at 50 yards with the crosshairs right at the edge of the FOV. It was closer at both 25 and 75 yards. If your eye is anywhere close to center, it's a non issue. Competition might require better accuracy, but if you miss that squirrel it's not because of parallax error.

Farther than the focus distance is a completely different story.
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Old June 20, 2011, 02:21 PM   #10
ZeroJunk
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I didn't have an issue with the accuracy, just focus.
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