plossl adjustment

[Derivious (Tyrone)]

Hi there I'm usually that guy who asks obvious and stupid questions and today is no different.
After buying a sw 9 mm plossl and using it for the first time I have noticed the eyepiece itself has a dial on it( the opening rotates) I assume it perhaps slightly moves the inner lenses around. My question is simply is this some form of fine focusing in itself or does it have a different purpose? I did not really notice any change using it on Jupiter last night, again I'm not sure what I'm looking for rotating it.

[blink138 (Pat)]

hello tyrone, i think it is there to give eye relief, you wind it "out" so that you can comfortably place your eye in the correct spot
pat