September 19, 2020, 04:37 PM | #1 |
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Parallax Adjustment?
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. Last edited by Bart B.; September 19, 2020 at 04:48 PM. |
September 19, 2020, 06:09 PM | #2 |
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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.
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September 19, 2020, 07:44 PM | #3 | |
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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. Quote:
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September 19, 2020, 11:41 PM | #4 |
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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?
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October 3, 2020, 08:06 AM | #5 |
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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".
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October 4, 2020, 09:44 AM | #6 | ||
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October 4, 2020, 10:18 AM | #7 |
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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 !!!
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October 4, 2020, 02:37 PM | #8 |
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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. |
October 4, 2020, 03:17 PM | #9 | |
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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. Last edited by Bart B.; October 4, 2020 at 03:43 PM. |
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October 14, 2020, 10:52 AM | #10 |
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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 |
October 14, 2020, 01:00 PM | #11 |
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October 14, 2020, 01:18 PM | #12 |
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"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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October 14, 2020, 01:34 PM | #13 |
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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.
Last edited by Bart B.; October 14, 2020 at 02:46 PM. |
October 14, 2020, 05:23 PM | #14 |
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October 15, 2020, 06:51 AM | #15 |
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.... delete
Last edited by Bart B.; October 15, 2020 at 07:03 AM. |
October 15, 2020, 09:02 AM | #16 | ||
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October 15, 2020, 09:26 AM | #17 | |
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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? Last edited by Bart B.; October 15, 2020 at 10:57 AM. |
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October 15, 2020, 09:30 AM | #18 |
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October 15, 2020, 10:57 AM | #19 |
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I have limited experience with scopes because nearly all the ones I have are LĂ©upolds, 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". |
October 15, 2020, 12:42 PM | #20 |
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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.
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October 15, 2020, 01:07 PM | #21 | |
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The difference is that rifle scopes are sighting systems and cameras are image recording systems. So the importance of parallax is greater in a sighting system, and image clarity is more important in an image recording system. The terminology used to describe what are two very similar processes reflect the primary goals of each system. Cameras can have issues with parallax; twin lens reflex (TLR) and rangefinder (RF) cameras have a great deal of parallax and users of those cameras have difficulty composing an image of nearby objects. The single lens reflex (SLR) camera was developed to minimize the effects of parallax by making the imaging axis coincident with the viewing axis. As a result, parallax in a SLR is essentially inconsequential and the discussion of parallax has largely been eliminated from photography. In a rifle scope, reducing sighting error is important along with a high quality image of the target. So we have a two step process (with adjustable objective/parallax adjustment) to focus the eyepiece on the reticle and then bring the target image into focus on the same plane as the reticle. This gives a sharp image and reduces/eliminates parallax. On a SLR camera where image quality is paramount, we have a similar two step process. The viewfinder diopter adjustment is used to focus the eye on the focus screen and then the lens is adjusted to bring the image into sharp focus. The adjustment process for the rifle scope and camera are similar, but the primary goal of the adjustment is different for each system. So we call one "parallax adjustment" and the other "focusing", even though they are essentially optically identical. Adjustable objectives were added to rifle scopes specifically to reduce parallax error, so that's why they were described as parallax adjustment.
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October 15, 2020, 01:37 PM | #22 |
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Adjustable objectives in scopes were first used over a century ago to focus targets on the reticle. With both target and reticle well defined, better accuracy was possible. Binoculars and some spotting scopes work the same way except their rear lenses move back and forth.
The parallax adjustment syndrome started when the distance focus knob was first used a few dozen years ago. Shame on whomever it was. Last edited by Bart B.; October 15, 2020 at 01:44 PM. |
October 15, 2020, 02:20 PM | #23 | |
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October 15, 2020, 04:03 PM | #24 |
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Yes. Internal focus (adjustment) is a good term. The first image plane is further back for closer targets. Therefore, you have to focus it in the second image plane at the reticle by moving the erector lenses.
Last edited by Bart B.; October 15, 2020 at 05:36 PM. |
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