Quote: The C11 is a light bucket and there is something to be said for that. My best images have been taken with the C11. So I am partial to keep it and using it. Although I also like my C6. It's nice to have options!
Quote:Personally I also have a C6 in addition to the C11. But the problem is that the time of exposure must be much longer with the C6 than the C11.
Quote:I have a very rock solid equipment including ADM Losmandy dovetail, saddle, mini-dovetail and clam shell tube rings for guide scope. Where the hell is the flex coming from?
Quote:Refractors have long aluminum tubes and they do ok with guidescopes. SCT's and RC's have two mirrors on supports, and they have flexure issues. The primary mirror is big and heavy, and it only has to tilt by microns or less to show a shift on the scale of pixels at f/10. Even with mirror locks it's hard to make a big mirror remain perfectly oriented to that level of precision as the OTA tracks the sky and the direction of gravity changes. For a c11 with no mirror locks, it will definitely have issues.With OAG - it's just not an issue anymore.Frank
Quote:Both C6 and C11 have same F/10 focal ratio and the exposure times should be similar. The C-11 has more light gathering power and reveal dimmer images but I believe the exposure should be the same as C-6 due to same focal ratio. Correct me if I'm wrong.Peter
Quote:An 11" Scope at F/10 will capture more light than a 6" F/10 on the same target. Not only will the 11" image scale be bigger, but the image will be brighter as well..
Quote:the idea of a 30min sub with the C11 seems a bit ridiculous... Its just not going to happen.
Quote: I will spare you the details but the conclusion was that aperture rules (if your mount is up to the task).
Quote:Thanks for the explanations. But I have some follow-up questions. If you use the same camera for both scopes, shouldn't the image size be the same? Also for a fair comparaison, shouldn't you compare both objects at the same size (by zooming on the object in the image with the smaller scope)?
Quote: If you use the same camera for both scopes, shouldn't the image size be the same? Also for a fair comparaison, shouldn't you compare both objects at the same size (by zooming on the object in the image with the smaller scope)?