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#1
08-29-2008, 08:53 PM
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Scope adjusting
A dumb question. Does adjusting the eyepiece focus change the point of impact? As I look through my bore-sighter as I turn the focus adjustment on the eyepiece, the cross-hairs look like they are shifting on the grid. Any comments?
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#2
08-29-2008, 10:02 PM
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That, my friend, is parallax. I'm guessing your scope does not have and adjustable objective lens. Bring your scope out side and point it toward something neutral like the sky and turn the eyepiece out until the reticle is nice and sharp. Look away for several seconds and then back a few times to make sure it is as sharp as it will get, when done, lock it and don't screw with it again. Even if your scope has parallax adjustment you need to do this properly or your eye will try and compensate until fatigue sets in.
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#3
08-30-2008, 04:45 AM
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No, you can't. You're only (supposed to be anyway) changing the focus on the reticle. If the reticle and the image are not in focus at the same time, then you have parallax. Any changes to the point of impact would be due to aiming errors from the out-of-focus reticle. Of course, it could be the result of something like whatever happened to that 3-9 Redfield I had when I was a teenager--when you cranked the power adjustment, the whole reticle turned
 Tim, you can only adjust out/create parallax from the objective side of the scope, not the eyepiece (ocular) end. There's a short article on it here. robert
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#4
08-30-2008, 06:48 PM
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Yeah robert I know, I'm assuming he does not have an adjustable bell, even if he did unless he gets a focus on the reticle FIRST he's never get all the parallax out, I must help out a guy with this about every other week at a match. It would be minimal on a March or Leupold 45x but if you use a Weaver 6x or Leupold 6x you can spend therest of your life piddling with the parallax adjustment to no avail. The lower the power the more important it is to set the eyepiece properly, just like the instructions direct you.
Read the third paragraph of the piece you refer, where the reticle and eye are in the same plane, that happens when you first focus the reticle. Last edited by tim simbari; 08-30-2008 at 06:53 PM.
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#5
08-30-2008, 07:16 PM
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make sure there's no wobble
I have a Mueller 4-16. At the range last week I was doing load workup. Things were a little fuzzy. I dialed the rear lens adjustment out to where things were a little clearer and my groups went from 3/4" to 3". Then I noticed the whole occular lens assembly had wiggle to it. Sure enough, if I looked through the scope and moved the lense, the crosshairs appeared to be moving 3". This was the "fast focus" eyepiece with no locking nut. I just screwed it back all the way in and went back to 3/4" groups.
Moral...Don't buy JUNK scopes. Charlie
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#6
08-31-2008, 05:44 PM
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Tim,
It's especially bad for someone like me. If you give me one of those slow-screw eyepieces, I'll fiddle with the damn thing all day long. Then on the other end, even with the easy parallax adjustments like the March, it's a slow progression of: Oops! too far. Oops! back up. Eventually, I get it narrowed down. Charlie, Curiously, that's one lesson we all seem to have to learn firsthand. Kind of like a rite of passage, we all have to beat our head on that wall.
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#7
09-02-2008, 05:17 PM
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I start by focusing the eye piece first, against the sky. All my scopes have the parallax adjustment on the end bell. Everything is fine, but my eyes are getting older, and my eyes change for the worse of course, and after a year or so, I have to refocus the scopes. Also, if my kids borrow my rifles, they always fiddle with the eyepiece to focus it for their own eyes. I just want to avoid having to go check the zero so often. I use typically 24 power scopes, and I never change the power. So, I guess that I am out of luck!
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