You think your scope is parallax-free when in focus?
HOW TO OBTAIN A PARALLAX-FREE SIGHT PICTURE WHEN YOUR SCOPE IMAGE IS A BIT FUZZY
Another accuracy issue comes from scope parallax. You probably have noticed that even though you have focused your target as clearly as you can, there still is some parallax present. Or, if you have eliminated it completely to the point that the reticle is still when you move your head around, you see that the target is a bit blurry. It is because both the ocular and objective lens are not properly adjusted so that parallax is nonexistent when the image (target) is sharply in focus. This is perhaps one reason why some shooters blame their scope for POI issues. Sure, you can minimize its effects by keeping a consistent cheek weld to counteract this issue (which is also good practice), but I think it is much better to feel confident knowing that the image is movement-free at a given shooting distance once a clear image has been achieved, especially when you do not have the means to keep the rifle very still while you do the “head dance” thing to check for it. Plus, I think it is also beneficial for shooters when a problem such as this is taken out of the picture (excuse the pun) for the sake of getting rid of one other obstacle in the quest to increase precision in shooting.
The common advice is to first adjust the ocular lens to a setting that projects a clear reticle to your own eyesight. For some scopes, however, when this is done first and it’s time to focus the objective lens to its clearest at the distance the target is at, both the reticle and target are still not on the same focal plane. I observed this on both of my Hawke Sidewinders some time ago.
Here’s how to correct the problem. First, you need to adjust the ocular lens until the reticle appears crisp – this is preliminary only. Next, view an object at a specific distance, for example a flower at 25 yards, and focus it by adjusting the objective lens until the object appears at its sharpest. When you have completed this, set your rifle still and fixed to the object then move your head around to see if there is parallax error. If there is, continue to adjust the objective lens until you no longer see the reticle move. You may find that you’ve gone beyond the setting from the one which projected a crisp image and now it is a bit blurry. Not to worry. Go back to the ocular lens and adjust it until the image is sharply focused then test again to see if parallax is nonexistent. If there is no more, you may find that the reticle has lost a bit of its sharpness/clarity (it shouldn’t be too drastic though). But this is okay because it should be your goal to have confidence knowing that your reticle won’t be moving around when you’ve got a nice, crisp sight picture. Once the ocular lens has been properly adjusted you no longer have to touch it, at least for the magnification level you set the adjustments at.
Try this test out. You may be surprised.
Cheers,
Spinj
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Viewing 9 replies - 1 through 9 (of 9 total)
Yep, I fully agree, thanks for opening the topic and sharing.
I read a lot about the method of setting the ocular lens by looking at the sky, some sources / books even say without glasses, if normally wearing some. A part from the “without glasses”, which didn’t work at all, the “sky-method” brought me closer to accuracy, but was not yet the solution.
Until I started refocusing, the way you and the article n3umw linked to, describe. This made it a lot better. Since the method seemed somewhat unconventional, I didn’t dare sharing.
Thanks again.
Cheers
I back what you say, have made the same experience and came down to the same results and workaround.
A good indicator for the issue is that when your gun groups at several spots on the target, which in my opinion comes from slightly different cheek weld, holding, eye relief between shots.
Can you confirm?
As stated in the first post, the reason why parallax is present even though the objective lens is properly focused is due to the ocular lens not being focused also. Parallax is effectively cancelled out and the target is correctly on the same focal plane when both of these are properly adjusted (the objective lens and the ocular lens). Both must be at a set position in order to create a one-dimensional sight picture, for instance, like what an art poster projects.
If you were to move your head while looking at any part of a poster, for instance, notice that whatever your eyes are affixed to (on the poster) nothing changes (moves) in terms of what viewing angle any part of the image on the poster is subjected to. Essentially, the goal a shooter should achieve to cancel out parallax is to, in a sense, frame a three-dimensional image and translate it into a still-image, like that of a poster.
Papa Schultz, the goal mentioned above is what one should aim for (no pun intended) when trying to avoid moving groups at any distance. Correctly adjusting the ocular lens right as I mentioned about in the original post has helped me to prevent such a problem. With that said, it is still crucial to maintain a consistent cheek-weld everytime when shooting for extreme accuracy.
Cheers!
Great topic guys!!
Here’s a video that breaks it down pretty good..
If your scope is a piece of shit at close range and some certainly are a fixed peep sight will work better for you at least out to 25 yds .
FROM : THE BIRDMAN
Hi spinj,
I back what you say, have made the same experience and came down to the same results and workaround.
A good indicator for the issue is that when your gun groups at several spots on the target, which in my opinion comes from slightly different cheek weld, holding, eye relief between shots.
Can you confirm?
Edit: btw @ n3umw, thanks for the link, very useful information, just read it after posting…
Page 78 of May 2015 Airgunners World has detailed instructions on proper way to set up a scope
Link to online magazine sample copy
http://edition.pagesuite-professional.co.uk/Launch.aspx?EID=d3e5da41-c956-4037-a4d2-1fec87222e1c
Thank you Zonk. The tuning method above is not to determine range/distance to the target, just parallax-error correction when the image is at its sharpest. On all of my scopes at the ranges I shoot at, I am able to cancel out reticle movement. The method described above is what I have done to tune my scopes so that when my eye has determined the best clarity of the target, parallax error is corrected. I have also confirmed this by letting the guns rest and moving my head in different directions. I believe parallax error still exists on some scopes even when users have clearly focused the image. The reason why the reticle still moves at this point is because the ocular lens has not been set correctly to prevent reticle movement when the objective lens shows its sharpest picture.
Good write up Spin, But the parallax adjustment is only a means to get you close the range your shooting. It’s extremely rare to fine a scope that’s dead nut on. And I’ve had many…..
Viewing 9 replies - 1 through 9 (of 9 total)
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You’re welcome Papa Schultz. The way I see it, more often than not, unconventional methods in shooting discipline can serve to make the difference between a good marksman and a wise sharpshooter. :thumb: I seek to become the latter.