[Ukraine Train]

I have a tasco 3-9x50 scope. The rear eye piece is threaded onto the tube of the scope and there is a knurled jamb nut that you tighten down against the eye piece. Is the eye piece threaded on just because that's how it's assembled or does turning it in/out serve an adjustment purpose?
http://my.stratos.net/~hummer21/scope.jpg

[Chuck Dye]

That is an adjustable ocular which is intended to allow you to focus your view of the reticle. With the lock ring loosened, mount the rifle to shooting position and turn the eyepiece til the RETICLE is sharp, ignoring the downrange view. Look away to distance for a moment or two, then check the focus again, looking to see if the reticle is sharp when you FIRST look, and fine tune. The idea (which I have never verified) is that the eye will accomodate substantial error, at an effort, and that by tuning until the reticle is sharp when you first acquire it, you can eliminate the effort. When you are satisfied, snug up the lock ring. Given the changes we suffer with age, this is not a once and forever process, you should recheck once and a while.