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Rifle Scopes Stoopid Question--Eyepiece adjust = Zero Shift

Grump

Gunny Sergeant
Full Member
Minuteman
Oct 23, 2008
1,216
12
So. Utah
Don't laugh too much. I'm an old iron sight guy who is just beginning to warm up to optics. Zeroing turrets is nice, but I still miss running up 6 clicks from the bottom and otherwise knowing exactly where I started from and where I am...

Anyway, I thought I heard someone say something once about fiddling with the ocular focus can result in the scope's zero shifting. My fair understanding of Newtonian physics has some doubts about this, but at least I'm smart enough to know when I'm uninformed. A wobbly ocular sure does shift the image, but it would seem to shift only the entire image, and do nothing to the target/reticle alignment of a FFP scope.

Thanks!
 
Re: Stoopid Question--Eyepiece adjust = Zero Shift

Adjust the ocular once and don't adjust it again until your eyes change. This way you don't care if changing it causes an impact shift or not.
 
Re: Stoopid Question--Eyepiece adjust = Zero Shift

Grump, In my experience the ocular isn't true to center line of focal plane.( Hope i'm saying this right} Anyway POI changes because of mechanical flaws in scope/lense alignment. I'm currently fighting POI changes from self-loosening lock rings. CNC's advise is spot on.
 
Re: Stoopid Question--Eyepiece adjust = Zero Shift

Well, that's a pisser.

Between eye fatigue some days and two different sets of contacts, my eyes *do* change.

What befuddles me is that sometimes even with no mirage and side-focus fiddling tuned in, the target is sometimes a bit soft-focused (not much) but the reticle never seems to fuzz up a bit.

I'll not futz with it until I'm ready to chase zero again.

In you experience, how much zero drift, min & max, have you seen happen?
 
Re: Stoopid Question--Eyepiece adjust = Zero Shift

Grump - the ocular adjusts the focus of the reticle. If the reticle is always sharp, the ocular is exactly where it's supposed to be (for you).