Refractor Collimation

I spent some time collimating my 4" refractor today with our club's new collimator. Basically I was squaring up the focuser and I first did so without the 2" diagonal. Then I put the diagonal in and re-tested. It is off about 1/2". No way to tweak the diagonal and it stayed the same no matter which way I turned everything. So, me thinks, since I always use the diagonal, I will square it up with the diagonal in place. Did so, but now I am wondering, "is that really the best alternative?"
What say the experts out in Astromart Forums Land?
(I've still got the laser and time on my hands! HA!)

Walt

1/2" is a lot, are you sure the laser is collimated?
Floyd

How much play does the laser have inside the
focusser? If you loosen the set screw that holds
the laser in the focusser just a tiny bit,
and then move the laser by hand, how much
motion do you get on the laser beam?

When possible, I try to do adjust the focusser
with the scope pointing straight down. This
helps reduce effects of any side-ways play
of the laser in the focusser.

Just wondering if the difference with the
diagonal is just caused by the laser and
diagonal having different play or different
seating in the focusser.

What refractor and what diagonal are you using? The Asian 1.25 inch diagonals are often miscollimated, I have had 3 of them, each has been miscollimated. The latest one was so bad the beam barely cleared the edges of a 80mm F5 objective. Easy to fix though.

jon