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  #1  
Old 05-07-2008, 11:12 AM
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Change in point of impact with variable scopes?


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Hey All,

Just a quick question..
I hear that with Variable magnification scopes the point of impact can change when using different magnification? If so, does this apply to all scopes of variable mag.? and how much does it effect the zero?

Thanks,
_Kar.
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  #2  
Old 05-07-2008, 11:23 AM
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That's mostly an old wives tale. When variable scopes first came on the market it may have been true, but today it's simply not. What good would being able to change the power be if you had to rezero every time you turned the power know up and down. It that were the case variable scopes would not exist.
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Old 05-07-2008, 12:13 PM
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ah, thanks for that,
someone told me that this occurs if the recticle is in the second image plane...
Is there a difference in having the recticle in the first or second plane?

_Kar.
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  #4  
Old 05-07-2008, 12:39 PM
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I sighted in my new Leupold VX-II on 12x power for 100yd and 300yd targets. The only changing in point of impact with scopes that I am aware of is what is called parallax. This is the apparent movement of the target from the reticle as you move your eye from the center of the eyepiece. The errors are very small, something like 2/10 of an inch at 100yds and 8/10 of an inch at 500yds.
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  #5  
Old 05-07-2008, 05:24 PM
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Quote:
Originally Posted by Kareir View Post
ah, thanks for that,
someone told me that this occurs if the recticle is in the second image plane...
Is there a difference in having the recticle in the first or second plane?

_Kar.

Yes a power change can effect POI on variable scopes, but as Bob pointed out with todays scopes that is rarely a problem to be concerned with, but is easy to verify if you are concerned.
A secound focal plane scope is more likely to have POI problems than a first focal plane scope. In a SFP scope to reticle always appears to be the same size. In a FFP scope the reticle increases in size as the power is increased.
Most American scopes are SFP and most European scopes are FFP. The FFP scope are the most rugged and less likely to shift POI.
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  #6  
Old 05-07-2008, 06:42 PM
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My Leupold Vari X 2,2X -7X hit 2 inches low at 50 yards,at 2X;when sighted in at 100 yards,at 7X.
That was about 10 years ago.
Frank
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  #7  
Old 05-07-2008, 07:17 PM
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Reticles in the first focal plane grow or increase in size as the magnification is increased. This will not be a problem on a hunting rifle, but on a target gun this can be a problem since the reticle conceals or covers so much more of the target. If what you need is a quality scope for hunting, then first focal plane is fine. I have both and generally speaking a scope with first focal plane reticles are higher quality.
As far as different magnification affecting point of impact, I agree with faucettb, this is generally not a problem except for cheaper poor quality scopes. Then anything can go wrong and usually does.
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