Hello - I met and spoke with a very nice gentleman at the NEAIC conference and he suggested I post this here. I really enjoy imaging with my ST-8300C and think it is a great one shot camera. But as I have been slowly tweaking my configuration and improving my results, I think I have noticed something odd which I believe might require a service. If you look at the attached fits images, you will notice good star shapes in the NW corner and center (majority of the image), but in the NE, SE, and SW corner they are oblong. I took one image with a Televue 101IS and then I took another using a completely different set up with an AT RC 10" scope. While the distortions are different shapes, they are localized in those same corners. The only thing I can think of is the CCD is slightly tilted? Could someone familiar with these cameras take a look and let me know what they think? I had very good guiding and I am on a Mach1gto equatorial. Thanks so much! Greg
I see the PacMan in this image with a 'screen-stretch' and "HalfSize" and "PinPoint Astrometry" 'USNO-A2 solve .
There's a lot going on with the Ritchey-Chretien telescope. At f/8 I really don't think sensor tilt is your main problem; I can see evidence of telescope collimation issues. In my experience RCs are an absolute bear to collimate properly (speaking from bitter experience here), and you can get quite the mess if it's wrong. The secondary needs to be precisely centered on the primary, and the camera needs to be precisely centered on both. This requires a special alignment scope - Takahashi makes one. Only once everything is centered perfectly can you adjust the mirror tilt for good collimation. If everything is not precisely centered there is no amount of tilting mirrors that can get the telescope to work properly. (Been there, done that!) The images from the TV101 do provide some suggestion of a modest sensor tilt diagonally. It's a lot smaller than what is going on with the RC, despite the faster optical system, which is why I'm concluding the RC problem is collimation. Although it's rare to have visible tilt on a smaller sensor, it would be much more obvious on faster systems. We're seeing only a small effect on the refractor. If there's a tilt Bill should be able to tweak it. Contact bill@sbig.com
