Quote:
Originally Posted by Jason D
Though it could be related to collimation, most likely it is not. A miscollimated scope could push a screw head into the lightpath inducing a spike but even for a perfectly collimated scope any mechanical intrusion into the lightpath will induce a spike.
Centering the spider vanes is less important than ensuring opposite vanes are inline or at least in parallel. If centering the spikes means introducing a small angle between opposite vanes then you will exacerbate spikes in your photo.
High precision is not required for this alignment. Ideally, you want to evaluate this alignment from a point where the primary apparent size is the same as the secondary mirror. Both should coincide as shown in the attachment. Then again, close enough is good enough for this alignment. Errors in this alignment will be manifested as an uneven illumination intensity in your photo. No spikes and no coma will be introduced with this error.
Which one are you getting? Are you getting one of the new astro XLK autocollimators from Catseye?
Jason
|
Wow! I am making my way though that thread now! A lot of information that is easily understood! Thanks!
I have just taken the scope arart to flock it, and during that time I gave the primary and secondary a good hit of air to get rid of some loose dust. Putting it back together, I didnt center the secondary, but I used a square sitting infront of the scope to make sure that the vanes were as close to parallel as can be, which will probably help, but I need to check some more.
I have a sighttube/cheshire combo, one question I have is, is it the same to align the crosshairs on the sighttube to the primary mirror centre dot as it is to make the 3 clips even around the outside? I did that today, the crosshair of the sightube is right over the primary dot, however when I rack the focuser in, the primary does not look centered at all on the secondary. I am thinking that it could be from a misalignment in secondary rotation?
And one last thing that I found when disassembling, was that the primary was actually loose in the cell!
I could easily move it around with my hands, which confirmed the nagging feeling I had. When I moved it before, I always thought I could feel and hear the primary moving but never knew for sure! So now it is clipped in tight and shouldn't go anywhere!
I ended up going with an Autocollimator made by a local guy, it is just a single pupil as far as I know, but it also was only 40$ delivered (I think, it was somewhere around that much) so I figured I would give it a go. The Catseye tools were a lot of cash to spend, and I am just a uni student who left high school so I cant really justify that extra cost, yet!
I think it should work out OK, but that thread is amazing, again, thankyou! I dont know how i didnt see it before!
Dan