How critical is a parallax adjustment or AO ?

[MIL-DOT]

I have a bottom of the line bushnell on an air rifle that has an adjustable objective, yet i see some much higher-end Bushnell Elites that don't have it.Lots do, but some don't. Their 3200 tactical fixed 10x doesn't have an AO (adjustable objective lens) or the side-mounted knob for it, yet i would have thought this critical on a scope like this.I'm definately lacking in knowledge here, as always, any help much appreciated......M.

 

[JohnBT]

Parallax adjustment is needed for short-range target shooting with rimfires and airguns. I'm mostly familiar with Leupold and Weaver scopes. Centerfire scopes are set to be parallax free at 150 yards, shotgun for 75 yards and rimfire for 60 yards. Rimfire scopes with AO, like the Weaver T-36 and Leupold 3x-9EFR & 6x-20EFR, will adjust down as far at 10 yards.

With AO you can adjust the scope for the exact distance you're shooting. A centerfire scope will work at very short ranges if you can keep your eye in the precise center of the eyepiece on every shot.

I'd try to explain the need to focus the reticle on the lens using proper terminology, etc., etc., etc., but I'm mess it up. Hold your arm straight out in front of you and point your finger up. Hold your other arm out halfway and point your finger up. Close one eye and line up your 2 fingers. Now, tilt your head from side to side and see how the position of your fingers shifts around in relation to the target. AO will, in effect, bring your two fingers together and eliminate the wandering.

Leupold FAQ on parallax www2.leupold.com/resources/MyInfo81/Answerbook/findanswers.aspx

I'll leave the need for AO at long range to somebody else.

John

 

[MIL-DOT]

Thanks John.....i've been Googling around today and have picked up alot on the subject. It's a little abstract, but i think i have the general idea. I'm really wondering if i really need it for the relatively long distance we shoot our air-rifle at ( 50,75,even 100 yards). I'm figuring since air rifle scopes tend to cost REAL rifle money, i might as well get a high quality scope that can fill in on my rifle should my Leupold MK IV take a fall. As we don't shoot competitively ( usually only 10 yards, i believe) then i might can get away with getting, for instance, the Bushnell Elite 4200 3-9x40 ( with no AO ) that i found a killer deal on.

edit: And sorry for all the attitude yesterday, i'm not sure what that was all about ! Guess i was having a bad day.

 

[tommer]

From the Leupold Riflescope Owner's Manual:

"Understanding Parallax

Parallax is the apparent movement of the target relative to the reticle when you move your eye away from the center point of the eyepiece. It occurs when the image of the target does not fall on the same optical plane as the reticle. This can cause a small shift in the point of aim.

Maximum parallax occurs when your eye is at the very edge of the exit pupil. (Even in this unlikely event, our 4x hunting scope focused for 150 yards has a maximum error of only 8/10ths of an inch at 500 yards.)

At short distances, the parallax effect does not affect accuracy. (Using the same 4x scope at 100 yards, the maximum error is less than 2/10ths of an inch.) It is also good to remember that, as long as you are sighting straight through the middle of the scope, or close to it, parallax will have virtually no effect on accuracy in a hunting situation."

Sounds to me like AO is overrated. Not unnecessary altogether, just more than most of us will use.

I've read somewhere, probably right on the Leupold site, that all Leupold scopes are airgun safe. This is apparently important because airguns have a unique recoil which is very desctructive to scopes that aren't designed to handle it. But you probably know that already if that's your sport.

 

[rero360]

not to hijack or anything, but how is the recoil on an airgun different and how is it destructive to normal scopes? my mom never let me have one as a kid so I'm pretty ignorant when it comes to airguns.

 

[WayneConrad]

Parallax causes the optic to show you a false aimpoint.

If you get your eye in the center of the eyepiece every time, parallax doesn't matter.

If you don't, it does.

That's why getting a consistent cheek weld is important: Because it makes it easier for you to put your eye in the center of the eyepiece.

Adjustable Objective eliminates parallax as a variable provided you know the range.

An optic without an adjustable objective is parallax free at just one distance. For centerfire optics, it's usually 100 yards; for rimfire, 50.

The larger the the difference between the distance you are shooting and the distance at which your optic is parallax free, the more parallax you will suffer if your eye is not centered in the eyepiece.

 

[MIL-DOT]

No hi-jacking,dude, good question.....The springer, or break barrel air guns have a unique two-stage kick, there's the normal push backward, then followed by a forward thrust when then cocked spring/bolt slams against whatever it slams against.It's this forward thrust that's most damaging.
( please forgive this less than technical explanation, but you get the idea.) Most scopes are not designed to handle this,even many otherwise high quality ones, and, from what i've read and been told, the reticle breaks loose,in some cases,after just a relatively few shots.
Some manufacturers, like Burris and Leupold, claim that all their scopes are air-rifle rated, but with some companies, it's only certain ones. The Bushnells, the Elite line in particular, are pretty highly advertised as being built to withstand the stresses of air gun use, and are commonly seen on high-end air-rifles.

And thanks for the response tommer, but from what i've gathered, parallax is the biggest concern at very long distances ( 700 yards +) and very short distances, which may be why AO's seem to be on virtually all airgun scopes.

 

[JohnBT]

This airgun site has some relatively inexpensive Bushnell suggestions, some with AO, some without.

www.airgunsbbguns.com/bushnell_air_gun_scopes_s/77.htm

I've been at the office for 2 hours and need to get back to work.

John

 

[MIL-DOT]

Actually,with the exception of the very cheapest one, they ALL had the AO.
I've been rooting around and making some calls. And i'm thinking i'll be better off with it than without it. Also learned that the SIDE adjustable Bushnell scopes are NOT air-gun approved, only the AO ones. I'm gonna send my less than stellar Bushnell banner back to them, and rather than repair it and return it, they'll allow me to upgrade to one of the Elite 3200 series directly from them, for a pretty fair price.So i'll save more than a few bucks on one of the scopes i was considering,or spend what i'd planned and get an even higher-end scope.
Anyway, thanks for the input......M.

 

[JohnBT]

That's a real good deal on a good scope.

One thing about a good scope is that you can always sell a gun when you tire of it and put the scope on the next one.

John