Scope setup and adjusting the ocular

A common method of adjusting the ocular is to set the parallax on infinity with the ocular lens turned in all the way.

Point the scope at a white wall or cloudy sky.

Look through the scope at the reticle for only a couple of seconds. Only long enough to see if the reticle is sharp. If not, turn the ring out just a little. Now look away. Close your eyes for a few seconds. Let your vision recover.

Repeat. 

This is the common method of getting the adjustable ocular set and is a starting point but I have been doing something different based on advice given in a blog post by the Crosman pro shooters. They recommend that it is more important to have the minimum amount of parallax through a scope in relation to any given person's eye than to have an arbitrary sharpness of the reticle. Your eye will quickly tend to focus on the reticle throughout a wide range of ocular adjustments. Hence the "only for a couple seconds" that is often recommended. But the adjustment of the ocular can serve for fine tuning other aspects of a scope also. Particularly noticeable at high magnifications of 25x and above.

Here are my tips:

Bench rest the rifle on a solid bench and bags.

Dial in the highest magnification you want.

Focus the side wheel on a midrange target that is close and complex enough to see differences in focus from the adjustments.

Now bob your head in the exit pupil of the scope image while adjusting the side wheel focus. Try to find the focus setting that has the minimum parallax. Any parallax will make the image of the target move around under the cross hairs opposite from the movement of your eye even though the target and the rifle are not moving. It can easily look sharp but still have +- half a mil of parallax for any given scope. Use the focus wheel to adjust for the minimum parallax while bobbing your head. The image of the target will appear to begin "rotating" around the axis of the cross hairs during extreme eye displacement with the bullseye still locked to the center when parallax is minimum, rather than seeing the apparent impact point move up and down and left or right on the target. Which will not necessarily be at the setting of the sharpest focus.

Then adjust the ocular toward getting the best compromise between image focus and reticle focus. Which may shift the best parallax slightly. Adjust for best parallax again and repeat. You may also find that compromising the cross hairs slightly this way will result in a sharper HD image down range than was available before even though both scenarios were adjusted for image focus as best as they could be. Tree bark is a good example.

The sharpness of the illuminated reticle versus the black is another concern where all of these considerations can be compromised with the adjustable ocular to get the least fuzziness and shift of the red in relation to the black during head bobbing.

I also tend to set the eye relief of the scope mounting slightly toward the too far range of the exit pupil ball which gives a slight dark ring around the image but shows that when this ring is centered, that your eye is precisely down the center of the scope.

I read a great tip for minimizing misalignment of the scope and rings which don't center it absolutely over the bore. 

Set the rifle up on a bench again and sight at a mirror. 

Simply rotate the scope until the cross hairs perfectly intersect the center of the bore.

Any level indicator should then be on the scope tube when the cross hairs are true to a plumb bob . Not the breech. It doesn't matter if the breech is level. Only that the cross hair is true to the bore and that the cross hair is level when on target.
 
Bravo! This needs to a pinned post. 

Probably the most overlooked step in setting up a scope.
I have read an untold number of posts where shooters have difficulty with their scopes, and I believe it all started with not having properly adjusting the ocular. The shooter needs to understand they are looking through TWO variable lenses, one focal and one magnification and they need to pair up.

Thank you for posting!


 
Depending on eye prescription, and build quality of scope as it pertains to optical compromises, adjusting the diopter can be a constant hassle. My eyes fluctuate due to type 2 diabetes so I'm adjusting both the diopter/reticle focus and the image focus quite a bit.

If I'm shooting a fixed distance I'll adjust both until I get the best compromise of lack of parallax and image focus. BUT in general for normal shooting, hunting, plinking, etc, I found out a long time ago I would rather have a clear image and suffer a little parallax error than the reverse. Parallax error can be mitigated for the most part by simply looking through the center of the eyebox and that means you might need to use different height rings and/or use some type of method to raise your face like using an adjustable cheek piece or a stock pack of some type. 

I found a $10 mod to raise the low cheek piece on my FX Impact which made a huge difference for #1 - my neck not getting tired/kinked during extended shooting sessions, AND #2 - getting my eye perfectly centered in the scope. Anymore I hate not having a rifle set up perfectly for my body features! Thankfully most of my rifles are fully adjustable!
 
Am I missing something here? My assumption is that in a quality scope the focus of the reticle and the focus of the image is on the same plane or can be adjusted to be so. Yes I have a scope that has this problem, but it's a low and Hawke scope. If the an image and reticle aren't on the same plane your eyes are always hunting back and forth trying to look at the reticle and the image. That's what happens with plain sights, you keep looking back and forth between the front post and your target. Far from ideal. That's why you buy a scope for to eliminate that BS. I have cataract surgery so I can't focus my eye anyway therefore if I have to compromise between the reticle or the image neither is ideal.
 
Thanks. That is the article I read some years ago. One more important point that is mentioned: "Always finish the rotation of the front of your scope or side wheel in the same direction (I.E. always go from near to far or from far to near)."

One fatal flaw with the otherwise high value Leapers scopes is a big vertical shift of about 1 mil depending on which way you last turned the focus wheel. Which makes me wonder if one way is better than the other. ie. which direction of shift would happen to have the lens element already "down" toward gravity so that the recoil didn't start to shift any follow up shots. None of my Hawke scopes have this problem and I just got a used Athlon Argos to try so I can report back on that.
 
Am I missing something here? My assumption is that in a quality scope the focus of the reticle and the focus of the image is on the same plane or can be adjusted to be so. Yes I have a scope that has this problem, but it's a low and Hawke scope. If the an image and reticle aren't on the same plane your eyes are always hunting back and forth trying to look at the reticle and the image. That's what happens with plain sights, you keep looking back and forth between the front post and your target. Far from ideal. That's why you buy a scope for to eliminate that BS. I have cataract surgery so I can't focus my eye anyway therefore if I have to compromise between the reticle or the image neither is ideal.

In a perfect world YES. That's the problem with eyes and optical compromises. Sometimes it all works together, and sometimes it doesn't. I don't understand all the give and take with lenses, etc but it seems like the higher the quality of the scope the less sensitive they are to those compromises. 

If you think about it, the retail price on a scope is probably 8 times what that scope costs the manufacturer to make. So what do we expect from a cheap scope that costs $40 to make. 

Though if one can't get both the image focus and the reticle focus acceptably clear, even though there is parallax error, the scope is faulty or it is poorly designed/engineering flaw.