Fixed power scopes and parallax.

[r3dn3ck]

So correct me if I'm wrong:

Given a fixed power scope (we'll say 10x for arguments sake and that I have a pair coming) with non-adjustable parallax and a factory parallax setting of 100yrds I would expect to see the target get a bit fuzzy at 1000m which would require adjustment of the focus to sharpen the target image. Adjusting the focus can bring the target into focus but the reticule will then be less focused, CONVERSELY, adjust the focus so that the reticule is in focus will fuzz the target image.

The above appears to be correct when I test those assumptions against very close targets (< 35 feet) with mid-magnification optics (6-12x).

Begin correcting me but please know what you're typing about.

As an aside, yeah, I've shot an astonishing amount at protracted distances but with age my vision has been rapidly degenerating and I've gotten used to something being out of focus and always having to futz with focus knobs is just something I expect so the actual effects never really struck me while I was banging away at far away steel. It won't matter a pair of fetid dingos kidneys either way in all actuality as my vision isn't good enough for it to but it is a matter of curiosity.

[jibben]

If I read my instructions right, The ones still in the box, in the dark corner where you put things that you should toss but you might have a need for it some day after you really do toss it... they said to focus the X not the target.

[r3dn3ck]

While your answer is appreciated and jibes with what I've always been taught, I'm not asking that question and it's immaterial. This is an academic question to make sure I understand a complicated behaviour of specific kinds of optical systems.

[thomae]

Redneck: My understanding (and, admittedly, I have no sources to cite) is that the ocular focus is strictly for the reticle focus, so that the crosshairs or reticle are sharp when your eyes look through the scope. To focus the scope for different target distances, you would need an adjustable objective lens, usually this is done either through a side knob mechanism or by turning the objective lens bell. These two actions (focusing the ocular lens, or eyepiece as opposed to changing the focus on the target based on its distance) are independent and if adjusting the ocular focus brings the 1000yard target into focus, it is purely optical coincidence.

Personally, I would choose focused crosshairs and blurry target. That's what I see when i shoot open sights, and for a lot of reasons, I think that's what you should "shoot" for when setting up your scope. If my crosshairs are sharp, I can still hit the center of mass on a blurry target, but the opposite does not necessarily hold true.

This is my understanding, but if i am wrong, someone smarter than I will correct me. I have never shot at 1000 yards, but I do have some fixed power scopes. ...and I DID NOT stay at a Holiday Inn Express last night.

Merry Christmas Eve.

[CJnWy]

The adjustment you are thinking of is to adjust the focus of the xhairs. Parrelax is what happens when you move your eye around and see the xhairs moveing off of target without the gun moveing. A good consistant cheek weld is about the only cure for shooting long range with a scope with no parrelax adjustment.
The target should be focused @ 100 and @ 1000. The difference is if you move your eye around the field of view in the scope the xhair will stay on target @ 100yards but move around the target @ 1000 yards
Hope this helps you understand cause I think I just confused myself :-)

[r3dn3ck]

No you nailed it for me. The effects of parallax are probably the most confusing bit to get straight but at least I can measure the effect of it at 1000yrds by moving my head around. This is actually a bit of a trick I sometimes use with my variables with A/O's. I'll move my head around while looking through the scope and adjust the objective until things focus up and settle down and that has gotten me some useful, if imprecise, ranging data in the past.

Cheek weld is a significant issue lately on my M70. It's just very very poorly stocked for anything approaching long range precision. At this point I'm weighing my options and trying to decide between a chassis system of some sort or a more conventional stock like a Manners or McMillan or getting another Richards microfit and doing some custom work to it. Personally I like the McMillans and some of the enormously expensive chassis systems but the Choate USS is so much less expensive and other than needing a going over with sandpaper and a file was nicely serviceable out of the box. Decisions decisions. I wish they made the AICS for long action post-64 m70's.