Take the time to PROPERLY set the Diopter FIRST!
Don't use the parallax to focus your picture, do the "head wiggle" test to see if the scope has parallax error, adjust it out, and then focus the picture with the ocular adjustment. Both of my Schmidts seem to be VERY parallax sensitive at ranges less than 200 yards.
I found that with the PMII and the Steiner Military 5-25 the parallax didn't coincide with the focus.
What I found is that my ocular was not properly set.
Setup at 100 yards and adjust the parallax until parallax error is eliminated (you can move your eye within the eyebox and the target does not move relative to the reticle). Now adjust the ocular until the target is in focus. Once I did this, the reticle was still in focus, and the target was in focus at the same point in the parallax adjustment where parallax error was eliminated, at any distance. You should only have to do this once, you should never have to touch the ocular again.
Maybe you two are having problems with the Parallax setting on your scopes is because
you're misusing the Ocular Lens (Diopter) and the Parallax adjustment. The Ocular (Diopter) is only used to focus the Reticle - once it's correctly set for your eye you should never have to touch it except to compensate for vision changes. Setting the Ocular/Diopter is the first thing that should be done after the scope is mounted for correct eye relief. The Parallax Knob is used to set the scope to be parallax-fee at a given distance. Parallax and focus aren't the same thing but they're closely related. The parallax-free setting and the point at which the target is in focus should be very close - this is because at that setting the target image and the reticle are on the same focal plane.
You two are adjusting the Parallax and Ocular (Diopter) in reverse order. After mounting the scope for correct eye relief you set the Parallax to Infinity, crank the Magnification to maximum, then slowly and carefully set Diopter. Setting the Diopter perfectly is tedious and painstaking work, but it's well worth the effort because you'll have a much easier time adjusting the scope to be parallax-free with a razor-sharp target picture (environmental conditions notwithstanding).
Below is
the correct procedure for Diopter (Ocular/Eyepiece) adjustment for both fixed and variable power scopes. The procedure is the same regardless of scope manufacturer, or whether the objective/parallax focus is on the objective ring or is a side focus type.
NOTE: If the scope is a fixed power unit skip steps 1 and 2 as they do not apply.
(1) Turn the magnification ring to maximum (highest power).
(2) Turn the Parallax focus to "Infinity" (the symbol for Infinity looks like a figure eight).
NOTE: Most non-side focus scopes use a ring on the objective bell to adjust parallax, and the distances are usually numbered. Side focus Parallax adjustment knobs may or may not have distances marked.
(3) Turn the Ocular Lens (Diopter)/Eyepiece all the way in (on PMIIs' that's counter-clockwise).
(4) Aim the scope at a cloudless section of the sky (you don't want anything except sky in the view, or else your eye will naturally attempt to focus on the object(s) in the view beyond the reticle. Also, the human eye is drawn to movement: Movement distracts the eye, and clouds are often in motion.
(5) Look at something nearby, but not too close, then look through the scope at the reticle. If the reticle is out-of-focus turn it a bit to begin to focusing the reticle, but look away from the scope.
Never look at the reticle for more than a couple of seconds when adjusting the eyepiece (if you look at the reticle for more than a second or two your eye will naturally begin to adjust to bring the reticle into focus - and you don't want this to happen.
You want to be able to look through the scope and see a sharply focused reticle immediately with your eye relaxed.
This cannot be achieved by continuously looking through the scope and turning the eyepiece into focus in one continuous motion because your eye will have already begun to adjust.
Note that the threads on Diopter adjustments are normally very fine, so you may have to turn the Diopter more than you might expect before any appreciable difference in reticle focus is discernable. You will most likely have to make several small adjustments before you get the reticle perfectly and finely-focused for your eye, but it is very important that you do so. A lot of shooters'
"chase the focus" because they didn't set their diopter adjustment correctly when they initially set-up the scope.
Remember, look away every few seconds and make small adjustments to dial-in the Ocular/Diopter/Eyepiece focus. Once you have achieved this, you should not adjust the eyepiece at all,
except to maintain sharp reticle focus as your vision changes over time
(it always does). You may want to put a pen mark on the eyepiece indexed to the index dot on the scope tube - if the tube doesn't have an index mark use a pencil. That way, if someone else shoots your rifle and adjusts the Ocular you know where to return the adjustment to.
If you cannot achieve simultaneous reticle and image focus after following the above directions for Ocular/Diopter/Eyepiece Focus, it is
possible that there is a problem with the scope.
NOTE: Setting the diopter at the
extreme end of it's adjustment range in either direction can affect the image focus. Also, since all of the lenses in a scope except for the reticle are curved, when using aggressively canted bases (as suggested by S & B for their PMII line) the eye may be pushed out of center of the lens very slightly blurring the reticle, although good eye alignment and head position pretty much eliminate this. I wear glasses (20/15 corrected) and I don't have this problem and I use 45 MOA bases with my PMII 5-25X[56] scopes. The quality of the lenses and coatings, and the user's vision, i.e. astigmatism, can also affect the reticle focus.
Keith