Adjusting for parallax error

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Nordic Norm

Nordic Norm

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Mar 14, 2023
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Manchester, Vermont, USA
Hi folks, parallax error is caused by the concave and convex shape of a scopes lens. All scopes have parallax error, some more than others. All can be corrected for by centering the sight picture on the lenses. To accomplish this the peripheral haze is used. Peripheral haze it the out of focus ring that can be seen by moving the eye closer to the scope. Move the eye until an even ring of blur haze surrounds the sight picture. This puts your sight picture in the center of the lens resulting in zero parallax error. Also, when mounting a scope, center the elevation adjustment, shim the scope to get close and fine tune with the adjustment. The closer the scope is to zero adjustment, the less the parallax/lens error.
I shoot 50/50 iron sights and scopes. The scope error is most critical when changing shooting positions. Centering a scope becomes an added step when shooting left handed behind ones right flank for instance. At 30m a 4x, set parallax rimfire scope can vary 3/4in in poi due sloppy parallax centering centering.
It isn't just because of rules that aperture sights rule competition shooting worldwide.
Hope this is helpful.
Shoot Parabolic
 
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Very good information. Good form can negate parallax error. I don't like SF/AO scopes for field use. I simply center my eye on fixed parallax scopes and have no problem. I use a 100 yard parallax 4x scope on a springer down to ten yards with zero problems. I've lost more shot opportunities fiddling with adjustments than shots missed from parallax errors. I think parallax errors are easily avoidable and greatly over estimated.

That said I do understand that adjustable parallax is necessary for people that want to shoot very close with higher magnifications. I think a clear sight picture and good form is more important than actual parallax settings.
 
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Mycapt65, "I've lost more shot opportunities fiddling with adjustments than shots missed from parallax errors."

I agree with that. It's funny how, in the first 30 years of hunting, I got along just fine without it. I have gone back to a lot of scopes w/o SF or AO.
However, I set the parallax to 40 or 50 yards (tree squirrel hunting), moving the objective lens forward 3/4 turn or so. It depends on the prey you are hunting and if a person has time to mess around with fiddling. The problem is when using high power scopes at close range. I don't mind the parallax error as much as I do out of focus; that is where SF or AO is excellent.
 
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Just my take on parallax and how to adjust it with either side focus or AO. I agree that if you can hold your eyebox/sight picture "dead center" you can eliminate parallax even with non-adjustable scopes. However, what I have found is the method usually recommended for "focusing" the ocular lens is usually the problem.

What I have always read or seen in videos is that you should point the scope either at the sky or a brightly lit light colored wall (white, etc) and look to see if the reticle is in focus. If not, give it a couple of seconds, adjust the ocular lens and try again... It is ALWAYS stated that your eyes will adjust quickly to FOCUS on the reticle. So, you have to do this many times to actually get the reticle focused. My experience is that you never get it truly focused and have less than the best parallax adjustment.

Think about that. YOUR EYES WILL AUTOMATICALLY ADJUST TO FOCUS THE RETICLE!

What you are really trying to do is get the focal plane of the reticle and the focal plane of the target/objective to be equal.

I started thinking about that and decided to use that to my advantage.

Forget about trying to "focus" the reticle to your eyes when adjusting the ocular lens!

Only pay attention to the parallax error when adjusting the ocular lens!
Your eyes will compensate/adjust to focus on the reticle.

If the reticle IS on the same focal plane (focus) as the objective, then you have no parallax error. That is the definition.

Using a stable rest of some kind and at the highest power your scope is capable of... focus your objective lens on the target.

Now move your head around while still being able to see the target through the scope. If you have significant movement of the reticle (parallax error) in relation to the target, adjust the ocular lens. Keep doing this until you have the least amount of movement of the reticle in relation to the target. Also, do this same thing using different distances to the target. 10, 20, 30, 50, yards... etc.

Eventually you will find the least parallax error over a certain distance.

As for focusing the reticle. That will happen naturally unless your eyesight is really bad. In that case, I'll make my next post in Braille just for you! (chuckle)

JMHO

All my best!

Kerry

P.S.

Using this method I have less than 1/8 inch parallax error out to 96 yards and imperceptible parallax error at ranges less than that using the Athlon Argos BTR 8-34x56 FFP and imperceptible parallax error out to at least 40 yards using the Aim Sports Alpha 6 4.5-27x50.

Wind is my main obstacle, except for that first shot with the Fortitude as the regulator creeps enough to make a 50-60fps difference for the first shot compared to the next few shots after it has been sitting for a couple of hours or more. For a hunter/pester, I prefer non-regulated guns when well tuned and kept within the pressure "sweet spot". That first shot is MUCH more important than a long shot string for me. (smile)
 
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Nordic Norm said:
--- Centering a scope becomes an added step when shooting left handed behind ones right flank for instance. ---
Click to expand...
Huh, I practice shooting from both sides, with the trigger in my right hand, aiming with the right eye, and left/left. I notice that the POI shifts between right and left, usually to the left and a little high when shooting lefty. I wonder if this is an optics centering thing, like you mention? Or maybe I'm canting the gun? Hmm, I'll have to set the gun down on a rest and look with one eye and then the other and see if the POA moves.
 
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Nordic Norm said:
Hi folks, parallax error is caused by the concave and convex shape of a scopes lens. All scopes have parallax error, some more than others. All can be corrected for by centering the sight picture on the lenses. To accomplish this the peripheral haze is used. Peripheral haze it the out of focus ring that can be seen by moving the eye closer to the scope. Move the eye until an even ring of blur haze surrounds the sight picture. This puts your sight picture in the center of the lens resulting in zero parallax error. Also, when mounting a scope, center the elevation adjustment, shim the scope to get close and fine tune with the adjustment. The closer the scope is to zero adjustment, the less the parallax/lens error.
I shoot 50/50 iron sights and scopes. The scope error is most critical when changing shooting positions. Centering a scope becomes an added step when shooting left handed behind ones right flank for instance. At 30m a 4x, set parallax rimfire scope can vary 3/4in in poi due sloppy parallax centering centering.
It isn't just because of rules that aperture sights rule competition shooting worldwide.
Hope this is helpful.
Shoot Parabolic
Click to expand...
Just reread the original post. The OP has no idea what causes parallax error. Although centering your view of the sight picture/eyebox CAN eliminate parallax error, it has NOTHING to do with the concave and convex shape of lenses.

If you are viewing the target near the outer edge of your scope's view box, there will be distortion and you will probably not be as accurate, but that is not, by definition, a parallax issue. It is more likely an issue of a cheap scope with poor glass/coatings.

Parallax error occurs when the target/objective and the reticle are not on the same focal plane. That is the definition.

Yes, parallax error is more pronounced the more off center your view is from dead center of the eyebox/sight picture, but that has very little to do with the concave/convex shape of the lenses.

Never have read anything that would imply, suggest or confirm what the OP claims is the cause of parallax error.

Look up parallax error. It is that simple.

All my best!

Kerry
 
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One scope mounted on one rifle used by a left-handed shooter and a right-handed shooter;I take 5 shots,he takes 5 shots,we are in competition,there is no difference in point of aim....I am a left-handed shooter and the scope was set up for me, yet the right-hander had no problems...
Sense would tell you to look at the center of the scope.
Yes indeed, the fine adjustment near your eye has a great effect on the clarity of your sight picture,I bet too many do not realize it.
 
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boscoebrea said:
One scope mounted on one rifle used by a left-handed shooter and a right-handed shooter;I take 5 shots,he takes 5 shots,we are in competition,there is no difference in point of aim....I am a left-handed shooter and the scope was set up for me, yet the right-hander had no problems...
Sense would tell you to look at the center of the scope.
Yes indeed, the fine adjustment near your eye has a great effect on the clarity of your sight picture,I bet too many do not realize it.
Click to expand...
Since the gun is setup for you, I would have to say that the other shooter was simply a better shot than you during this competition.

At least that is what common sense would suggest to me. I usually just say it was the wind... (chuckle)

Maybe I don't understand your meaning of the "fine adjustment near your eye..." comment?

All my best!

Kerry

P.S.

Sorry, I assumed you lost the competition which you never said one way or the other.

My apologies.
 
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I personally set my parallax adjustment to match a measured range, so 50 yards on the parallax adjustment at 50 yards then I set the ocular bell to give me the clearest focus possible at that range. There may still be parallax present by doing it in that manner, but it tends to give me a clear view at the indicated range.
 
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