Can anyone explain this scope adjustable objective issue?

FirstFreedom · February 22, 2005, 09:41 PM

I've got this Burris Compact/Mini 3-9x32 (or 33, I forget) with an adjustable objective that goes down to 7 yards. This is nice for the rifle it's on (an RWS 350 airgun), EXCEPT for this state of affairs: When shooting at any given range, when the scope's adjustable objective is set for that same range, it should therefore obviously be in focus - but it's not; it's out of focus. However, at that proper range setting, I can see that the parallax-free status is indeed correct - it's parallax-free at the range that matches the setting. But so, when I adjust the scope's AO upward so that it looks in focus, I have a clear sight picture, but there is parallax present, which I can see by moving my head around and seeing the shifting point of aim. For example, at 10 yards, if the AO is also set on 10 yards, then it's blurry, but parallax-free. I have to crank it up to 25-30 yards on the AO setting for it to be clear at 10 yards, but then there's parallax. So I'm damned if I do, damned if I don't. I'm not sure which is better, but usually I get the focus clear and just try to center my eye to eliminate parallax. But it certainly appears that the scope is not doing what it ought to do, which is, both focus AND eliminate parallax at the correct setting for the given range. So, is this Burris crap, or is this a common occurence that simply cannot be engineered away in any scope of any quality? I suppose that if no one knows, no biggie, as I can test this issue with my other 3 scopes which have AO on them (I have 2 AO Bushnells, a Scopechief and a Banner, and 1 AO Leupold VXII). It's just that I don't shoot nearly as short of ranges with those rifle/scope combos as I do with my airgun which sports the Burris, and it's the short ranges where the parallax AND focus problems (BOTH) are greatly magnified. But the Banner Bushnell goes down to 10 yards/meters, so it should be a simple matter to test this issue with that one.

scottys1 · February 22, 2005, 10:54 PM

You might check the focus of the reticle which can usually be set independently of parallax and see if it makes a difference. Set up at a distance and parallax setting where you know it's parallax free and play with the reticle focus at the rear of the scope and see if there is an improvement.

thelast2 · March 1, 2005, 04:53 AM

My first question is did you buy this scope new or used? You should set AO to the desired range and then adjust the focus with the reticle eyepiece. If that dont work I would say there is something wrong with the scope. I have a burris though mine is higher powered and have no problems with it the burris scopes have a forever warranty and if you bought the scope used I would send it in to burris and have it checked. If you bought it new I would take it back to where ever you bought it and have them take a look at it and see what they think, because something dont sound right. The burris scopes are some of the better qaulity scopes out there so that isnt the issue the issue would be was the scope dropped or if a used scope, abused by a previous owner.

Just as a side note the eye relief on that scope is 3.75"-5.0" so make sure you have the scope mounted accordingly.

FirstFreedom · March 20, 2005, 11:04 PM

OK, thanks (a little tardy). I was prepared to kick myself for something so simple, but no that's not it, because this scope does not HAVE a rear eyepiece focus adjustment - the only thing adjustable is the AO...hmmm. It's weird - still works reasonably well however.

LHB1 · March 25, 2005, 03:07 PM

FF,
It is my understanding that the purpose of Adjustable Objective is to set the scope to be parallax free at the indicated range. Would be nice if it could also set focus of the scope itself but I think that is usually done separately using the rear eyepiece. Most common recommendation for focus that I remember is to point scope at clear blue sky and turn rear eyepiece until cross hairs are sharp instantly when you first look thru the scope.

Good shooting and be safe.
LB (ex 1911 Forum junkie)

ps: Are you sure the rear eyepiece doesn't turn? Most such adjustments are not marked like the AO adjustment.

pps: Have you contacted Burris Service dept for their comments on your AO adjustment and scope focus functions? See what they say.

February 22, 2005, 09:41 PM	#1
FirstFreedom Junior member Join Date: May 31, 2004 Location: The Toll Road State, U.S.A. Posts: 12,451	Can anyone explain this scope adjustable objective issue? I've got this Burris Compact/Mini 3-9x32 (or 33, I forget) with an adjustable objective that goes down to 7 yards. This is nice for the rifle it's on (an RWS 350 airgun), EXCEPT for this state of affairs: When shooting at any given range, when the scope's adjustable objective is set for that same range, it should therefore obviously be in focus - but it's not; it's out of focus. However, at that proper range setting, I can see that the parallax-free status is indeed correct - it's parallax-free at the range that matches the setting. But so, when I adjust the scope's AO upward so that it looks in focus, I have a clear sight picture, but there is parallax present, which I can see by moving my head around and seeing the shifting point of aim. For example, at 10 yards, if the AO is also set on 10 yards, then it's blurry, but parallax-free. I have to crank it up to 25-30 yards on the AO setting for it to be clear at 10 yards, but then there's parallax. So I'm damned if I do, damned if I don't. I'm not sure which is better, but usually I get the focus clear and just try to center my eye to eliminate parallax. But it certainly appears that the scope is not doing what it ought to do, which is, both focus AND eliminate parallax at the correct setting for the given range. So, is this Burris crap, or is this a common occurence that simply cannot be engineered away in any scope of any quality? I suppose that if no one knows, no biggie, as I can test this issue with my other 3 scopes which have AO on them (I have 2 AO Bushnells, a Scopechief and a Banner, and 1 AO Leupold VXII). It's just that I don't shoot nearly as short of ranges with those rifle/scope combos as I do with my airgun which sports the Burris, and it's the short ranges where the parallax AND focus problems (BOTH) are greatly magnified. But the Banner Bushnell goes down to 10 yards/meters, so it should be a simple matter to test this issue with that one.

March 1, 2005, 04:53 AM	#3
thelast2 Senior Member Join Date: February 6, 2005 Location: Eagle River, Alaska Posts: 118	My first question is did you buy this scope new or used? You should set AO to the desired range and then adjust the focus with the reticle eyepiece. If that dont work I would say there is something wrong with the scope. I have a burris though mine is higher powered and have no problems with it the burris scopes have a forever warranty and if you bought the scope used I would send it in to burris and have it checked. If you bought it new I would take it back to where ever you bought it and have them take a look at it and see what they think, because something dont sound right. The burris scopes are some of the better qaulity scopes out there so that isnt the issue the issue would be was the scope dropped or if a used scope, abused by a previous owner. Just as a side note the eye relief on that scope is 3.75"-5.0" so make sure you have the scope mounted accordingly. __________________ "Genius Has Limitations, Stupidity Does Not"

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February 22, 2005, 10:54 PM	#2
scottys1 Senior Member Join Date: May 21, 2004 Posts: 316	You might check the focus of the reticle which can usually be set independently of parallax and see if it makes a difference. Set up at a distance and parallax setting where you know it's parallax free and play with the reticle focus at the rear of the scope and see if there is an improvement.

March 20, 2005, 11:04 PM	#4
FirstFreedom Junior member Join Date: May 31, 2004 Location: The Toll Road State, U.S.A. Posts: 12,451	OK, thanks (a little tardy). I was prepared to kick myself for something so simple, but no that's not it, because this scope does not HAVE a rear eyepiece focus adjustment - the only thing adjustable is the AO...hmmm. It's weird - still works reasonably well however.

March 25, 2005, 03:07 PM	#5
LHB1 Senior Member Join Date: March 25, 2005 Location: Houston, TX Posts: 1,545	FF, It is my understanding that the purpose of Adjustable Objective is to set the scope to be parallax free at the indicated range. Would be nice if it could also set focus of the scope itself but I think that is usually done separately using the rear eyepiece. Most common recommendation for focus that I remember is to point scope at clear blue sky and turn rear eyepiece until cross hairs are sharp instantly when you first look thru the scope. Good shooting and be safe. LB (ex 1911 Forum junkie) ps: Are you sure the rear eyepiece doesn't turn? Most such adjustments are not marked like the AO adjustment. pps: Have you contacted Burris Service dept for their comments on your AO adjustment and scope focus functions? See what they say.