IFN, M81, M82 with Sony A7S

[sharkmelley]

Maurice, that's a very interesting comparison.  Thanks for taking the trouble to do it

My vignetting is certainly more severe.  I think this is because the diameter of the E-mount fitting is rather too small for the full frame sensor - at least when mounted on a scope rather then using a lens..

One thing that is also quite noticeable is how my stars have been severely attenuated by Sony's "star eater" algorithm.

One reason I went for the mirrorless Sony is that I reckoned there would be less weight on the focuser than using a full frame DSLR so I'm hoping it will give pin-sharp stars over a greater range of conditions.

For this paricular image, I certainly need to do a reprocess, paying more attention to bringing out colour.

Mark

[ammonthenephite]

Sharkmelley, have you had a chance (or even the desire) to try the higher exposures on the camera to see how well they come out?  I read one very indepth review that claimed that all the way up to ISO 51k looked very useable, even more so when stacking. 

It would be interesting to see a side by side comparison of stacked images, one set at ISO 2000 and the other at the higher ISO's up to 51k.  This camera has really peaked my interest.  While nothing can really make up for a good mount, the thought of combining this with either my ed80 (on an older skyview pro mount that doesn't track well much beyond 45 seconds) or on my c8 with hyperstar (on that same mount, eak!) at those higher ISO settings truly, truly intrigues me, as it would lower my exposure times considerably.  Plus I could use the camera for all the other types of photography I like to do.  As opposed to upgrading my mount, which can only be used for astronomy, heh.

[sharkmelley]

The camera is certainly very useable up to very high ISOs but unity gain is at ISO 4000 and there is nothing to be gained by going higher than this except for a slight reduction in the already negligible read noise.

By using higher ISOs you simply lose dynamic range i.e. stars and bright objects saturate much earlier.

I generally use ISO 2000.

Mark

[Ohan Smit]

Fantastic capture  

Well done on the processing and thanks for the in depth information you've given so far concerning this camera 

Ohan