How to use AO or side focus scopes.
 

Here is summury of what I learned from another forum. If you would like to read the original it is on the Long Range Hunting Magazine forum. Here is what I learned it is very helpful and others should read and know this too. The AO and side focus knob are the same but need to be operated in different fashions. When we get a new scope the first thing we should do after we mount it is adjust the eye poece focus so our cross hairs are crisp and clear. That is the job of the eye poece focus adjustment. To use the AO on a scope with the parallex adjustment on the objective of the scope is fairly simple. This can be adjusted in any direction up or down the yardage marks no issue. It is used to remove the parallex from your scope and focus your sight picture at differnt ranges.
Now for the side focus knob it does the same job as the AO but is a little more fussy to use but not really when you know how to do it. After you have focused your cross hairs with your eye piece it is time to learn how your side focus knob works. The big thing to know is that the side focus will not work right if you adjust by lets going up in range from 100yds to 400. The side focus in order to work right must be turned from the stop at infunity down to 400yds. Now I have not checked yet but apparently there are screws or a screw on this knob that llows you to set your infinity mark. What you do is find an oject out past 800 or more yds and turn your side focus knob all the way to infinity until it stops. Now slowly turn it back until your image is perfectly clear and in focus also check your crosshairs do not move if you move your head but don't touch the rifle while moving your head. This will be your infinity. Now loosen the screw on the side focus knob and turn the knob until the infinity mark matches the hash mark on the scope and tighten the scre. You now have infinity set and I believe it said your csope will stop here at this point from now on. The thing to remember from this point on is when ever you are hunting or target shooting and you know your range turn the side focus to infinity and turn it back down until your target is nice and clear and make your shot.
On the forum the author goes into much more detail on how this all works so it is worth the read. I just thought if they did not know that others should have this info as well. This fall while hunting I tried it and I believe my side focus scope was a lot clearer and I got my deer. I just hope this will help others to understand their scope better.

not exactly.... just being clear will not give you a precise adjustment, turn to infinity, then turn it back until as you move just your eye while looking through the scope, the crosshairs do not move off the target, if you bypass that point, you must turn it back to infinity and start over, its just how the adjustment is designed. on my scopes (2 loopy mark 4's and a night force NXS when the parallax is gone, the image I see goes beyond clear and just starting to fuzz, its what I do and it works, have killed a dozen deer past 1K.
RR

Have you done this before wit your scopes RR by that I mean adjusted the infinity mark. I do not doubt your experience just wondering if the fuzzy picture may be because you missed a step. Also do your loupy's and Night Force have that screw on the side focus knob. This sounds stupid but I have never checked my scopes I always forget when I am around my guns.
I did mention the cross hair thing I was just long winded about it.

just checked my scopes, the mark 4's have a set screw where you can change the focus, but infinity is not just past 800 yards, ask the guys who shoot 3 miles. so what is infinity? its farther than you can see, basically an endless range. my night force NXS (which is superior to the loopy's for long range work) has no way to change the knob.
RR

Ya I checked after I posted a reply my Swaro has no adjustment either. I don't know why the author of the article I read used 800 or more to set infinity mark. The part of the article I found interesting was the point you always start at infinity and work down with side focus scopes. I truly had no idea about that fact.