Parallax Adjustment?

B

Bart B.

New member
When did folks start calling the process of adjusting a scope sight objective lens system to focus on a distant range or target to "parallax adjustment?"

Especially when the aiming eye is on the scope optical axis, there's no parallax to adjust regardless of what range the objective lens system is focused at.
 
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I have a Redfield 4x12 rifle scope and instruction book from about 1973 and it uses the term parallax adjustment, so the that term has been in use for at least 50 years.
 
Parallax is a real thing, but very much over stated. I think that what Bart is saying is that many people confuse focusing the scope for adjusting parallax.

For most shooters, at the ranges they shoot parallax is a non issue. Most shooters, and their most rifles aren't accurate enough for it to be a factor. For some elite shooters at extreme ranges maybe.

A quote from Leupold owners manual.

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 same4x 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
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When the image of the target coincides with the reticle, there is no parallax. When did people start calling this parallax adjustment, instead of focusing? No clue. It doesn't matter, does it?

-TL

Sent from my SM-N960U using Tapatalk
 
Paralax, focus.... Whatever you want to call it.
I don't mind the adjustment on the side of the scope too much.
But i hate the adjustable objective out at the end of the scope!
Especially useless for use on a "hunting scope".
 
jmr40 said:
Parallax is a real thing, but very much over stated. I think that what Bart is saying is that many people confuse focusing the scope for adjusting parallax.
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I'm not sure that I've read anyone confusing the two; on the contrary this subject seems to show up mostly when a scope is correctly adjusted for parallax at a specific distance but the target isn't in sharp focus. The scope gives correct focus or parallax adjustment, but not both at the same time.

jmr40 said:
For most shooters, at the ranges they shoot parallax is a non issue. Most shooters, and their most rifles aren't accurate enough for it to be a factor. For some elite shooters at extreme ranges maybe.
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Parallax is a big deal at short ranges, so rimfire and airgun shooters deal with it a lot. Quite a few scopes have parallax set at 100 yards; using one of those at 30m will show a substantial parallax shift with head movement.
 
Nothing new, just effects scopes/optics

Parallax is an optical effect and has been around longer than rifle scopes. It's effect is present, in many optics/sights. I first encountered this term while involved with the reading of instruments and a common term, was Parallax-Error. It's real and been around for as long as we have been on this earth.. ..

https://en.wikipedia.org/wiki/Parallax

Be Safe !!!
 
What Zukiphile said and it's a pretty big deal with any scope in my opinion unless your just a casual shooter.
I've seen many a scope that had a couple of inches of parallax at 200yds when the objective was set in focus for me and I have 20/20 vision. Add that to typical group size error of .75 moa and your gun is a 3.5 gun at 200yds, 7moa at 400yds before factoring in any vertical stringing.
 
Double K said:
I've seen many a scope that had a couple of inches of parallax at 200yds when the objective was set in focus for me and I have 20/20 vision.
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That happens when the scope's eyepiece is set to focus your vision in front of or behind the reticle and the objective lens focuses the target image at that point instead of the reticle.

Adjust the eyepiece to focus your eye on the reticule first, lock the eyepiece in place, then adjust objective lens to focus on target to eliminate parallax at target ranges.
 
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That's right. The reticle should be in focus always. The target is brought to focus by parallax adjustment. Then the target image coincides with the reticle, and hence no parallax.

Parallax indeed exists everywhere when marker (reticle) is not on the same plane as the scale (target image). There have been a lot of interesting mechanisms to reduce or eliminate parallax.

-TL

Sent from my SM-N960U using Tapatalk
 
"Except when the aiming eye is on the scope's optical axis."

To me, if I adjust parallax properly, it does really matter if my cheek weld is consistent or not. POI will be the same if my eye is on- axis or off-axis.
 
Dave P said:
"Except when the aiming eye is on the scope's optical axis."

To me, if I adjust parallax properly, it does really matter if my cheek weld is consistent or not. POI will be the same if my eye is on- axis or off-axis.
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If you're a good marksman shooting accurate stuff, inconsistent cheek welds will degrade accuracy. The bore axis angle changes while bullets go through it. Inconsistent angles and resistence from recoil axis to center of mass holding the rifle changes where the barrel points when the bullet leaves.
 
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jmr40 said:
Parallax is a real thing, but very much over stated. I think that what Bart is saying is that many people confuse focusing the scope for adjusting parallax.
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That may be what Bart thinks people are saying, but the purpose of an AO (Adjustable Objective) scope isn't focus, it's to adjust the zero parallax distance to match the distance you're shooting at. And the reason for doing that, of course, is so that parallax isn't a factor even if your eye isn't directly on the scope axis for every shot.

std7mag said:
Paralax, focus.... Whatever you want to call it.
I don't mind the adjustment on the side of the scope too much.
But i hate the adjustable objective out at the end of the scope!
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No, it's not "whatever you want to call it." Words have meaning. Parallax adjustment is not the same as focus. The adjustable objective that you dislike is for adjusting parallax to zero at the distance you're shooting. If you don't care about that or you dislike it, then don't buy scopes with adjustable objective lenses.
 
Aguila Blanca said:
That may be what Bart thinks people are saying, but the purpose of an AO (Adjustable Objective) scope isn't focus, it's to adjust the zero parallax distance to match the distance you're shooting at. And the reason for doing that, of course, is so that parallax isn't a factor even if your eye isn't directly on the scope axis for every shot.

No, it's not "whatever you want to call it." Words have meaning. Parallax adjustment is not the same as focus. The adjustable objective that you dislike is for adjusting parallax to zero at the distance you're shooting. If you don't care about that or you dislike it, then don't buy scopes with adjustable objective lenses.
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What's the difference between a SLR camera lens focusing a subject on the screen or film and a scope focusing a target on the reticle?

What dimension changes in scope lenses when you adjust parallax with the side knob?

What direction does the scope adjustable objective lens system move when focusing a closer target on the reticle, forward closer to the target or backward further from the target?
 
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I have limited experience with scopes because nearly all the ones I have are Léupolds, lots of older ones mostly VX-3's and VX-2's.
Per the scope instructions I use the eyepiece/ocular lens to focus the reticle so it's sharp and clear while looking at a blank white wall.
Then use the adjustable objective to focus on the target.
Here's where myself as well as other target shooters I've personally known have had trouble, occasionally when the objective is focused at distances inside 100yds{sometimes farther} as is the case in ARA 50/50 and 22 silhouette there is parallax in the scope. To me parallax is having the reticle appear to move on the target when changing head position behind the scope in spite of the reticle and target being in perfect focus.
I as well as others I've shot with have sent the scopes back to Leupold describing the problem and they come back "fixed".
 
Whomever it was to first put in print that any scope has a parallax adjustment had no idea the confusion it would cause. All that knob on the left side did was move two erector lenses back and forth focussing the first image plane on the reticle. 1st plane image from a fixed objective lens moves back as target gets closer; typically about 2/10th inch going from 1000 yards to 50. An adjustable objective lens needs to move forward that much for the same range change.

https://patents.google.com/patent/US4643542A/en
 
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