dark current noise

alexisgreat wrote:

Astrotripper wrote:

But I have to warn you, at f/10, even the Moon will require very high ISO to keep the shutter fast enough. As for imaging deep sky objects at long exposures, you definitely could use that focal reducer to get it down to f/6.3.

Thanks! So you have a MAK too?

Yeah, I got a SkyWatcher Virtuoso that came with tiny little 90mm MAK that's rather useless. But I also got a slightly larger 102mm one that I could actually use to image the moon and sun (with proper solar filter of course). For example something like this:

see it on flickr

or this:

see it on flickr

To complement my 8" SCT, I also have an ETX-90RA, 90mm MAK. I think the E-PL6 may be the only interchangeable lens camera still made that the tabletop equatorial mount of that telescope can handle!

Well, the problem here will probably be the shutter shock. No idea how your telescope will play along, but that little 90mm MAK I have is so susceptible to shutter shock, that even very fast shutter speeds are useless. It's basically completely useless for astrophotography unless you use fully electronic shutter (or you shoot video for later stacking, but video from Olympus cameras is very bad for this).

I know you said I shouldn't worry about all the junk between the camera and telescope, but should I still definitely leave the correct image diagonal out? The only reason I was thinking of using it is for imaging near the zenith it will rotate the camera 90 degrees so the camera isn't near the base of the mount.

If the camera can fit there, it's not a problem. That's when that tilting screen fill come in useful. But if it can't fit, than I guess you won't have much choice but to try.

Either way, don't be afraid to experiment. Just try both ways and see how it goes. There's nothing better than first hand experience.