how important is adjustable parallax for LR shooting?

Parallax diminishes as range increases. As Suputin adds, ensuring your eye is centered on the eye-piece (occular lens) and no shadow is present in the image, then there is no parallax. It is simpler to have a side or end focus but the problem is not enough to get upset over. Common hunting scopes are focused to be parallax free at 100 to 125 yards by the factory.
 
A target scope ought to have a parallax adjustment.

Having said that, if the scope otherwise does everything you need/want it to do, there is a shooting technique that you can use which will allow you to entirely work around the need for a parallax adjustment. Briefly, that technique is to mount the scope so that your eye is either "too close" or "too far" to the scope, so that you see only a partial image in the eyepiece. When you line up your shot, ensure that this partial image is centred in the eyepiece - if it is, then this means that your eye is perfectly centred for that shot and for every shot that you aim using this technique.

(Pet peeve - the parallax adjustment of a scope is most definitely *NOT* the scope's focus adjustment. Even though it affects the focus of the scope. Even though most people call it "the focus". Even though some scope manufacturers refer to their scopes having "side focus adjustment". Even though Leupold, who you think should know better, actually has the word "focus" printed on the knob on the side of my 8.5-25X scope, the idiots.)
 
chuck nelson said:
It's so easy it's elementary.
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I'll stick with my Parallax adjustable scope, at least the ones I have. Now that I think about it, about half my scopes do and have don't. I have never really worried about it one way or the other. All of those are "low" powered - 10X and under.

I have not really checked to see if parallax goes away at longer ranges. Hopefully I will remember next time I get out for some distance shooting. I do notice it at say 100 yards with my 25x scope. I just need to remember to double check it when testing loads at the range.
 
(Pet peeve - the parallax adjustment of a scope is most definitely *NOT* the scope's focus adjustment. Even though it affects the focus of the scope. Even though most people call it "the focus". Even though some scope manufacturers refer to their scopes having "side focus adjustment".
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Athough I hear you, the people have decided. Most users of the adjustable objective had long ago shortened the name to "AO" for brevity. Side parallax adjustment doesn't exactly flow off the tongue. Neither does "Side AO except that isn't right 'cause its not the objective lens that's getting adjusted, it's the erector assembly that's being cammed back and forth and it's for reduceing the apparent movement of the crosshairs to the target and not for focusing even though it does focus things, that's the function of the adjustable eyepiece that is actually for focussing the reticle even though it does focus the image at the approximately the same time, but that doesn't count cause the manual says it doesn't and if push came to shove it has a small effect on parallax as well, but don't even think about that 'cause you should be thrilled by a fuzzy image and a clear crosshair knob. It's on the side".
 
chuck nelson said:
It's so easy it's elementary.
Click to expand...

+1 on this. It is simple, basic shooting technique and form. For parallax to be at its worst, you would need to have your head position so poor that you were seeing only part of the field of view. Centering your eye behind the ocular takes practically zero time to do, and doing so eliminates parallax altogether. It also eliminates the time required to adjust the parallax setting if a target appears at a distance other than that at which you are preset. A scope with fixed parallax, once adjusted once for your eyesight, has a sharp clear image and crosshair at any range. The fuzzy image seen through an AO-equipped scope set at the wrong distance is a high price to pay for a nonexistent advantage.

And, yes, centering your eye is easy to do even from those legendarily difficult "field positions" that so many are fretting about. Just practice! A difficult, long-distance hunting shot is not the time to be learning how to do this, and it's not the time to be fiddling with an AO either, unless you are trying out for an appearance on "Best of the West".:rolleyes:
 
Except when I have checked it at 100 yards, the cross hair does jump with eye position, and I am seeing the full eye piece, no shadow. When I adjust the parallax knob, the cross hair variation with eye position can be reduced to damn near nothing.

Again though, I do not recall checking this at long distance. Other effectively say the parallax effect is inversely proportional to distance to target so maybe it makes no difference.

Also, most scopes up to 10X do not have parallax adjustment so magnification must play some effect too?
 
rnbra-shooter said:
A target scope ought to have a parallax adjustment.

Having said that, if the scope otherwise does everything you need/want it to do, there is a shooting technique that you can use which will allow you to entirely work around the need for a parallax adjustment. Briefly, that technique is to mount the scope so that your eye is either "too close" or "too far" to the scope, so that you see only a partial image in the eyepiece. When you line up your shot, ensure that this partial image is centred in the eyepiece - if it is, then this means that your eye is perfectly centred for that shot and for every shot that you aim using this technique.

(Pet peeve - the parallax adjustment of a scope is most definitely *NOT* the scope's focus adjustment. Even though it affects the focus of the scope. Even though most people call it "the focus". Even though some scope manufacturers refer to their scopes having "side focus adjustment". Even though Leupold, who you think should know better, actually has the word "focus" printed on the knob on the side of my 8.5-25X scope, the idiots.)
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Thank you! I'm glad someone mentioned the difference between focus and parallax.

In bench rest you definite need parallax adjustment. Whether at 100 or 1000 I notice that even the slightest movement of the head will give you parallax if it is not compensated for. Mind you at 100 it's extremely small but where .001" counts it's a big deal. If parallax wasn't a factor in bench rest then 100% of the shooters wouldn't have the adjustment on their scopes.

Mystic's trick of using the parallax adj to see the mirage better works great.
 
Dogleg said:
:confused: You lost me.
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Dogleg:

Seeing the mirage at different areas between the target and you really helps reading the wind more clearly. What happens with wind flags (if you are lucky to have them at your range) is that they give you an indication of the wind direction and velocity (somewhat) AT that height of the flag; NOT at the height of the bullet's path. It is helpful but at lower velocities, the mirage is your friend (or enemy on gusty or cloudy days when you cannot see it).

Sometimes when the winds are near dead or dead, the mirage is your only indicator of a mild wind that might need a very (oh so very small ) tiny windage correction. That kind of correction that keeps you inside the VBull ring when others are shooting Bull-5's. Ask me how I learned this....

About 10 years ago, I was score keeping for a DOUBLE Distinguished US Army SF sniper qual'ed shooter at CFSAC. We got yakking just before our prep time began. I started my habit of tossing grass. He said that was a waste of time since wind was not the slightest. I said, "WTH?" and he explained how to short focus on the 200 m mound in front of me with my spotting scope. As I looked at the surface of the 200m mound, I could see the mirage / heat waves just transitioning from straight up, to walking from right to left , and then it began running, then back to walking.

I watched as he placed a 1/4" MOA right windage and he warned me to lower my power ring on my spotting scope and scan for all the sighters as the OTHER targets came up as Bull5's and his target held the VBull. :D

Those of you who are wondering how a civvie like me could be shooting at CFSAC... back in 1999 (and years before) DCRA's NSCC was shot concurrently WITH CFSAC matches and there were a few of us civvies on the firing line. Timk was with me and were stood out like sore thumbs :D Next time you are in the Jr Ranks bldg (old mess hall in front of Charlie Range), look for the composite CFSAC pictures of 1999, 2000, and 2001. Look for us civvies in the sea of Green/Cadpat uniforms. And some of you are wondering how a US trooper could place 1/4" MOA clicks on his rifle... he was shooting a match prepared USAMTU tweaked M16A2!

Anyways, that was one super valuable lesson I learned from the US Special Forces trooper! He left me with a parting quote: Experts read the wind, Masters read the mirage!

I will never forget that lesson! :cool:

Cheers and peace out!

Barney
 
Hungry,
I know the difference between parallax, focus and the knob;) Since I assumed that MPlayer also does, I was curious as how he could get any useful info on mirage from the apparent movement of the crosshairs. Apparently he just likes to call his parallax adjustment his parallax, no law against that.
 
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