Does my zero change with a power change on a variable scope?

[Ned Ludd]

I would like to know if a power change on a variable power scope changes my zero.

I'd say a powder change can change one's zero for any scope as it depends on the change in velocity that the powder produces. If the velocity is the same, then NO, it doesn't. But if there's a significant change in velocity, then YES, the zero will need changing as the POI has in relation to the zero one had set. For example, higher velocity results in lower POI.

Power, not powder...as in the scope magnification setting, not the little dark kernels that go inside the cartridge.

 

[Straightshooter1]

Power, not powder...as in the scope magnification setting, not the little dark kernels that go inside the cartridge.

Yup. You're right.

Funny how I read that more than once at the time and still read it wrong. I'd make poor proof reader.

 

[Ned Ludd]

Yup. You're right.

Funny how I read that more than once at the time and still read it wrong. I'd make poor proof reader.

Don't feel bad. After reading your post, I had to re-read the original three or four times just to be sure it didn't actually say "powder". LOL.

 

[ILya]

In a FFP scope, by design, the POA does not change with magnification. You can have apparent change if your eyepiece and sidefocus are not setup correctly: as the exit pupil gets larger you can induce and error, but if everything is set up correctly the POA should remain dead on.

With SFP scopes, POA can and usually does change with magnification, but with high quality scopes it is such a small change that you can not measure it without specialized instrumentation. Naturally, my earlier comments about eyepiece and sidefocus adjustments apply here as well.

The only variable SFP scope where POA can not change with magnification, to th ebest of my knowledge, is March's EP Zoom.

ILya
www.darklordofoptics.com

 

[Hermantk]

I'd say a powder change can change one's zero for any scope as it depends on the change in velocity that the powder produces. If the velocity is the same, then NO, it doesn't. But if there's a significant change in velocity, then YES, the zero will need changing as the POI has in relation to the zero one had set. For example, higher velocity results in lower POI.

Higher MV can result on a lower POI at very short distances but a higher POI at longer distances. A change of 15fps in MV will result in about a 5" elevation difference at 1000 yards. Not a big deal at all when hunting but a very big deal in competition.