During galaxy season I did an image of M101 because there weren’t a lot of suitable targets for my 80mm refractor’s relatively wide field of view. Most galaxies are small and really demand longer focal length to do them justice, but M101 was fairly large and by utilizing drizzle integration I could extract every last bit of resolving power from my small refractor.
The result can be found here.
I was incredibly happy with this image and was waiting out the interminable spring clouds to move on to another target. Then I was invited to participate on an imaging team at Sierra Remote Observatories. That team was using a Planewave CDK14 and an FLI ML 16803. It was an offer I couldn’t refuse.
But, there were some kinks to work out in the system and the team and I worked to resolve them. We ended up using M101 as our test target and although we had to throw away a lot of data, there was still quite a bit of usable left over. I decided to process to see what it would produce.
That result can be found here.
This video shows the difference in resolving power between the two systems and talks a little about why that is so. But, we users of small refractors shouldn’t despair. The images they produce are still fantastic even if they can’t quite live up to what the larger system can produce.
There are four factors that combine to determine the ultimate resolving power of your imaging system. They re the optics, camera, tracking and seeing. You only have direct control over the first three but it’s the last one, the seeing, that puts the ultimate limit on what we can get out of a system, at least for traditional long exposure deep sky imaging techniques.