Tests with Canon Ra.

[John W]

Continued my tests with a new Canon Ra camera attached to my Meade LX600 10" scope (alt az). Both pics are single exposures of 30 sec. each of
the Tarantula nebula and 47 Tucanae. Thanks for viewing, John W.

[strongmanmike]

Well done John :thumbsup: I notice the stars are a little triangular though?. This usually means there is some astigmatism being induced somewhere..?

Mike

[JA]

That's a really decent amount of signal and depth to collect in a single 30 second exposure :thumbsup:

On the issue of the star shape, also mentioned by Mike, I'm guessing somewhat but, is there a diagonal in use that might be causing such?

Best
JA

[John W]

Reply to JA. Yes there is a diagonal in use - should it be removed? Thanks.

[JA]

I like to call the middle of NGC2070 "the little guy":D and I always look for him whenever I see a Tarantula image.

On your image I noticed that the image of his face was mirror reflected left/right - the edge of his tongue was on the opposite side of his mouth to what I'm used to seeing, suggesting the possibility of a left/right mirror image /flip so I suspected that there was an extra mirror or diagonal in the system. That coupled with the slightly triangular star shape, from a telescope that I was not aware of such issues with, given its reputation and corrector optics (ACF), I thought that the diagonal might be a possible cause to investigate for potentially improving the star shape.

With a full frame sensor you have all its wonderful light collection abilities, but also its challenges: that of seeing to the extreme edges of the image circle where even tiny inconsistencies will be seen. If it were me I would try and see if there is any play in the diagonal which when screwed down might possibly tilt the optical axis slightly which might potentially introduce some tilt related aberrations. So as a long-winded answer to your question about removing the diagonal: I would certainly try it, (if it is easy to do with your existing gear) to see if it has any effect on the star shape. Even with the diagonal attached it might also be beneficial to as a diagnostic trial provide some additional physical support to the camera to reduce the load / moment on the diagonal.... and of course check everything is nice and tight.


Best
JA