Parallex Adjustment - Do you use?

idig4au

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How important do you think it is of having the capability of adjusting a rifle scope's parallex is on a hunting rifle scope? Many of my rifles scopes have this feature, but I can only think of one instance when I have actually used it while making a long range shot on an animal and then it was only to slightly improve the clarity of the sight picture. The parallex didn't match the range of the shot, at least for my eyes anyway.

I would be curious as to what everyone's opinion is on this and if you think this feature is important when selecting a rifle scope for general big game hunting for 500 yards or less type shot. Pro's and cons of this ability. I question the utility of this function on a big game hunting rig when using like a 12x max power scope at these ranges.

Thanks
 

wapitibob

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I used mine. I set it by moving my head up/down rather than dialing the distance. As much as my crosshairs moved up/down there's no way I'm not using it.
 

rfurman24

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It is not that big of a deal out to around 3-400 yds. As the distance grows the parallax becomes more and more important. There are zero cons to having an adjustable parallax that I can think of. On non adjustable parallax scopes they set it to one setting vs you being able to change it for different conditions.
 

Matt Cashell

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It is not that big of a deal out to around 3-400 yds. As the distance grows the parallax becomes more and more important. There are zero cons to having an adjustable parallax that I can think of. On non adjustable parallax scopes they set it to one setting vs you being able to change it for different conditions.

I actually like non-PA scopes for hunting in a lot of circumstances. The reasons are this:

1. It is one less thing to worry about.
2. It won't be accidently moved to one extreme or another.

Parallax error is not as significant as most people believe. In fact, there is NO parallax error if you have your eye perfectly centered behind the exit pupil, as it should be with proper shooting form.

A good discussion of parallax error is here:

http://www.rimfirebenchrest.com/articles/parallax.html

If you calculate it out, you will see with 100 yard corrected scopes, maximum PE isn't really big until you are WAY out there (or way in close). The maximum error is even smaller further out with scopes corrected at longer ranges like Swarovski's ballistic reticle equipped scopes (200m corrected), and Zeiss' Rapid Z scopes (300 yards corrected). And again, those MAXIMUM errors are when your eye is lined up at the very edge of the exit pupil (Who would shoot like that?), if you leave your eye centered, there is no error, regardless of the setting. It is the same reason you center your eye in the peep of an open peep sight.

With all of that said, while IMO parallax adjustability isn't required for even long range hunting, there is nothing wrong with a parallax adjustable scope, and I do adjust parallax in the field when I have time. I just make sure its not "walking" on me before I shoot.
 

rfurman24

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BB you are correct in your statement that basically the shooter creates the parallax error and good shooting form will all but eliminate errors but in field shooting positions one can not always get into the best position for the shot. I agree it adds one more thing to worry about when all I want to do is line up the reticle and pull the trigger. I completely disagree about its importance especially at distance. I do quit a bit of long range shooting and with parallax set at 100 to 200 yds it can be off by a couple of minutes or more at 1000yds. If you were completely perfect in your form it would not matter but as stated before field position does not always allow that.
 

Matt Cashell

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Actually, using the formula from the above linked article, with a 50mm objective scope parallax corrected at 100 yards the maximum parallax error at 1000 yards is 8.86 inches or about 0.8 MOA. With a 200 yard corrected scope the maximum error is 3.93 inches. And that is the MAXIMUM error if your eye was at the very edge of the exit pupil. The error is much less if you put your eye even close to the center.

So even with a poor shooting position, you should be able to get the error to a very small level.

I also shoot to long ranges often, although most often at steel and rocks. I have a Swarovski Z3 that is corrected at 200M. Although this is not the rifle I shoot to 1000 yards, I do take it to 800, and haven't had trouble with parallax error.
 

rfurman24

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I 100% agree with the math of a 50mm max PE of .8 from point of aim. That would actuallly equate to a max PE of 1.6 moa if you calculate the max PE from max to max instead of max to POA like in the article. I am in no way saying that someone is going to shoot that way. I am simply saying if you are going to take an ethical shot at an animal 700, 800, 900 yds, etc. you need to make sure everything is perfect. I don't believe everyone should be shooting at those distances. Having equipment errors in excess of .5 moa is unacceptable to me. It is already bad enough when you miss a wind call. I also shoot a 56mm scope. I also have no problem hitting things at those distances but when I am shooting paper and shoot a group larger than .5 moa I have found the cause to be due to parralax error. It is also much more pronounced with more magnification and larger objective.
 

Matt Cashell

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rfurman24,

First off,

This is a great discussion for optic/rifle nuts like us, and I appreciate the conversation. Thanks.

Second,

You are right, that that is maximum error from POA. However, the only time that would matter is if you are shooting for groups at those distances. It is conceivable that you could shoot one shot of the group from one side of the exit pupil, and the next from the other, giving you max error in both directions, but each shot still wouldn't be experiencing greater-than-max PE.

Interestingly, according to the proof of the equation, Parallax error is not affected by magnification at all, but it does make it easier to see.

Parallax error is not an equipment error, but an operator error.

For shooting groups, and load development, I also prefer parallax correcting scopes, but I can make do with non-PA.
 

rfurman24

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BB I agree with everything in your last post. I did not mean to say magnification induced more PE but rather made it more noticeable as you stated. My statement about equipment errors was intended to mean errors involving the equipment as opposed to things like reading the winding getting the correct range etc.
 
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