Tonight was my first night out with the new CGE/C9.25/Megrez 90 combo, and my first night polar aligning a GEM. I never did get better than half a degree from the pole, but it was good enough for experimenting.
I noticed immediately that the collimation of the C9.25 was way out, which wasn't too surprising given the long shipping route to get to me. 20 minutes later I had the collimation set satisfactorily, and was having a quick look at Saturn right next to the full moon. Not bad contrast, considering the two were only a few degrees apart.
I decided to see how well the mount performed unguided at low focal lengths, so I hooked the 40D up to the Megrez, with the WO 0.8 FFIII as well. Given that the moon was full, I was a bit limited in how long a frame I could shoot. I did 5x2 minutes on M42, and 4x2 minutes on the old horsie. Dark frames were used, but boy, did I need flats. Oh well, I wasn't expecting much since tonight was a night to experiment. The processed images took a lot of stretching, but the alignment and tracking were good enough that I didn't get trailing at 2 minutes, anyway.
I noticed that towards the edge of the frame the stars went diamond shaped, I assume that this is due to the flattener not being orthogonal to the objective? Granted, it does seem to rotate with the angle from the centre, implying that maybe my reducer to sensor distance is off. I'll have to experiment a bit on that one.
its great getting out with some new gear, the 9.25 has a good reputation for being a sharp scope, i look forward to seeing some images from you once you sort out the little bits.
I think I figured out the problem with astigmatism on the reducer, we'll see tonight. Hopefully I will have regenerated enough blood to survive the mozzies again. Last night was brutal, I think I need to make a mozzie netting shield around the scope.
