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Parallax Questions

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FALex View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FALex Quote  Post ReplyReply Direct Link To This Post Topic: Parallax Questions
    Posted: March/10/2013 at 22:29
hey folks, long time lurker, and huge SWFA customer here...just had a question in regards to why some scopes have parallax adjustment, while other do not.

Specifically, I noticed many fixed power scopes do not have parallax adjustment.  Is parallax a non-issue when the magnification is fixed?  

Secondly, I am seriously considering the SSHD 3-9 and I noticed it does not have parallax adjustment, either.  Is this because the magnification range is relatively low compared to higher magnification scopes?

Sorry if these questions are ridiculous, but I am looking at getting into a scope for my .223, and I don't want to spend a lot of cash.  However, every scope I have owned has parallax adjustment, so I have never noticed and have never had to ask these questions.

Thanks all for the help!
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rugerguy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rugerguy Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 05:04
Okay here we go....

To put it as simple as possible the parallax adjustment or "adjustable objective" (AO) as they are refereed to is just a focusing knob. Much like on binoculars.

Reason why you don't see them very often is because your everyday run of the mil hunting scope is used for shooting game out past 100 yards. And past 100 yards is when the parallax no longer has an effect on the quality of the image.

You see them more often in small caliber rifles/air guns (especially airguns a AO is a must) like 22 rim-fire or 17 hmr because you take the majority of your shots under 100 yards where the image becomes blurry so the AO is used to counteract the blur and make it clear again.

And to answer your question, NO. Parallax adjustment has nothing to do with fixed or variable powered scopes. It is just a preference, if you are taking a shot under 100 yards do you want to be able to focus in and get a crystal clear image? Most of the time the image is not going to be bad enough to affect the shot. I could be wrong here but from my experience these types of scopes are very popular for target/bench shooters where they need a crisp focused view on the target at a fixed range.

You need to also keep in mind that it takes time to adjust the parallax setting and this is why you don't normally see these on hunting scopes, because it is a hassle to adjust the scope to the measured distance that you might have to guess. Which also brings me to another point. People also prefer these because it can be used as a range estimating device. When the image becomes clear you look to see what the distance is on the scope and that gives you your distance to the target. This becomes less accurate as you increase in distance but still useful.
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rugerguy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rugerguy Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 05:08
What do you plan on using this .223 for?
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Bitterroot Bulls View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bitterroot Bulls Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 10:26
I hate to disagree with Rugerguy, but:
 
Parallax adjustment is primarily intended to bring the image at the target into the same focal plane as the reticle, to eliminate parralax error.
 
Low mag scopes often don't have parallax adjustment because parallax error (seen as the reticle appearing to move on the target as the eye is moved behind the scope) is not as noticeable at lower magnifications.
 
Image focus is a secondary effect of eliiminating parallax error.
 
As far as using a marked PA knob to estimate distance, that would be problematic, given that most knobs don't have accurate markings.
 
This is the best discussion around on parallax, IMO:
 
-Matt
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rugerguy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rugerguy Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 13:10
Originally posted by Bitterroot Bulls Bitterroot Bulls wrote:

I hate to disagree with Rugerguy, but:
 

Parallax adjustment is primarily intended to bring the image at the target into the same focal plane as the reticle, to eliminate parralax error.

 

Low mag scopes often don't have parallax adjustment because parallax error (seen as the reticle appearing to move on the target as the eye is moved behind the scope) is not as noticeable at lower magnifications.

 

Image focus is a secondary effect of eliiminating parallax error.

 

As far as using a marked PA knob to estimate distance, that would be problematic, given that most knobs don't have accurate markings.

 

This is the best discussion around on parallax, IMO:

 



This is correct. I was just trying to explain it in layman's terms.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdgray Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 18:58
Scopes without a means to remove parallax, are basic hunting scopes. Parallax error will ruin a group, so target and precision rifle scopes will usually have a means to remove it, either with side focus or AO. Parallax can also be avoided by being in perfect alignment behind the rifle. Most centerfire rifle scopes are factory set to be parallax free at 150yrds, where a 22 scope is set at 50yrds. Unless your shooting at those distances, there will be some parallax error in your scope. The extra expense for an AO or side focus scope is well worth it, if your shooting for groups.
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FALex View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FALex Quote  Post ReplyReply Direct Link To This Post Posted: March/11/2013 at 19:34
I guess I should have mentioned, I would be using this rifle for an all-purpose rig; it bangs steel, shoots tiny groups and whacks varmints with dizzyingly precise shots. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Onewolf Quote  Post ReplyReply Direct Link To This Post Posted: March/13/2013 at 13:59
I am a relative newbie, but....
 
My rifle has a Bushnell Elite 3200 10X fixed scope on it and the only significant thing that I don't like about it is that it does not have an adjustable focus/parallax.  It's no problem shooting small <1/2MOA) groups at 100 yds, but when shooting at 1000 yards at 6"-10" targets I have to be extremely careful to align myself PERFECTLY EVERY TIME because the reticle will move all over with the slightest eye movement.
 
But with this scope for $125 (NET) it annoys the other guys in the long range shooting club with their $2000-$3500 scopes that I shot just as well as.  Big Grin
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