I have an old Weaver T-16x scope that seems to be in really good condition. I put it on a rifle, to test for accuracy, and as per our club rules, went to the 50 yard line for the initial sight in. The scope was very blurry at 50 yards

The adjustable objective on this scope is marked with a micrometer type scale, rather that being marked for yardage. And of course the eye piece is threaded onto the tube.

So, my question is, is the objective used to focus the scope, or is it used for Parallax adjustment and the eyepiece is the focus?

When you say "the scope was blurry" do you mean the crosshairs? I use the focus adjustment to focus the crosshairs and the objective lens to focus the target.
Peter.

Well, the target was certainly out of focus. I will have to take it back out to see if the cross Hairs were out as well.

Ocular focuses the reticle, objective focuses the target. My limited experience the distance markings on objectives are only close. I set focus at infinity, look thru scope at a clear sky and bring reticle into focus with eyepiece. Then when looking at a target I focus objective until I have crisp target image, if this makes sense?
C.G.B.

riverman, it is possible that your scope may not focus down to 50 yards. You don't need to go to the range to test this out, just look out of your window or door and focus on a distant car or house using the objective lens adjustment. Crosshairs can be focussed just by resting the rifle on a bed or something, looking through the scope and adjusting the ocular (eyepiece).
Peter.

When done the target and x-hairs should be in focus with little or no parallax.

Actually I believe your scope will focus down to 50 feet for smallbore purposes. Ocular and objetive comments should solve your "focus" problems.
Often while serving as a range officer and walking the line of shooters I see new shooters using scopes with the ocular lens adjusted very tightly, no threads showing at all. I suppose there could be situations where that would work, but 9 out of 10 times when asked if I could look at their scopes/rifles and inquiring if I can adjust the ocular lens a bit, they look dumbfounded! Usually I adjust until there is some close to .25" of thread showing and ask them to take another look and again, majority are very happy with the improvement. Reticle/crosshairs suddenly become very clear!!

Funny, I have one sitting on my desk now. It does focus down to 50 feet. I agree with what MFD posted.

Rich

Well, riverman has not posted in a while, so we don't know what the resolution, or even the original problem, was!
Peter.

The problem was, my lack of knowledge concerning these old target scopes.

After this weekend's Bullseye match, I brought out the rifle/scope, followed the sugestions offered here, and was shooting some pretty respectible groups in no time flat.

All is well that ends well.

Good! Thanks for posting.
Peter.