Shiraz
06-08-2010, 12:23 AM
Found out what the annoying little tag on the front of the secondary holder in my GSO f4 8inch Newt is for - it stopped the secondary mirror from falling into the tube when the double sided tape securing the mirror lost it's stickiness. The mirror remained pretty much in place, but could move by small amounts in arbitrary axes as the attitude of the scope changed.
results - minor scratching on secondary mirror surface, lots of low quality subs.
symptoms - collimation wander, variable strange star shapes (worse with MPCC in place), variable differential flexure when tracking.
Looks like the secondary may have been loose for months, while I was chasing MPCC/camera alignment, focuser slop, tube flexure, primary mirror mounting, collimation etc. etc. Refractors have a lot going for them.
results - minor scratching on secondary mirror surface, lots of low quality subs.
symptoms - collimation wander, variable strange star shapes (worse with MPCC in place), variable differential flexure when tracking.
Looks like the secondary may have been loose for months, while I was chasing MPCC/camera alignment, focuser slop, tube flexure, primary mirror mounting, collimation etc. etc. Refractors have a lot going for them.