Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Apr 09, 2017, 02:43:30

Title: Jupiter and Great Red Spot 8-April-2017
Post by: MarkS on Apr 09, 2017, 02:43:30
GPCam2 IMX224 on Celestron C11 with x2 Barlow and ZWO Dispersion Corrector

2000 frames of 5ms exposure time with high frequency jittery seeing.  I'm pleasantly surprised how well this came out given the conditions.  I was getting a frame rate of 70FPS with a crop of 640x480.

(http://www.markshelley.co.uk/Astronomy/2017/jup20170408.jpg)

The quality of the camera is astonishing.  Remember I measured the read noise at around 0.7e  An individual frame at 5ms exposure time had a higher quality than much slower frame rates on previous cameras.

Mark
Title: Re: Jupiter and Great Red Spot 8-April-2017
Post by: Carole on Apr 09, 2017, 08:45:57
Very nice Mark, my camera only goes up to 30fps (DBK).  The dispersion corrector seems to make a lot of difference, I am struggling with that.

Carole
Title: Re: Jupiter and Great Red Spot 8-April-2017
Post by: Fay on Apr 09, 2017, 08:55:12
Lovely Jupiter Mark, detailed and smooth

Fay
Title: Re: Jupiter and Great Red Spot 8-April-2017
Post by: MarkS on Apr 09, 2017, 09:34:28

Quote from: Carole
Very nice Mark, my camera only goes up to 30fps (DBK).  The dispersion corrector seems to make a lot of difference, I am struggling with that.

Don't obsess about frames/sec.  From all the forums you get the impression that a high frame rate is key.  But it's not the whole story: if high frame rate results in individual frames that are too dim and have too low signal to noise then you are shooting yourself in the foot and the final stack will be too noisy to do any decent wavelet transform. 

This was my 4th attempt this week.  Previous attempts were ruined by cloud or fog coming over just as I was about to start shooting.

Mark
Title: Re: Jupiter and Great Red Spot 8-April-2017
Post by: Kenny on Apr 29, 2017, 17:02:22
Wow. Really amazing image Mark. Stunning.
Title: Re: Jupiter and Great Red Spot 8-April-2017
Post by: The Thing on May 04, 2017, 11:23:14
Lovely Mark, the 11inch has such better resolution than my 8inch SCT. I find short exposure e.g. your 5ms more important than very high frame rates Carole, as its the quick shutter that freezes seeing. A lot of 12ms at 30% gain (my settings usually) frames at 30 fps is as good as at 130fps. And the old worry about planetary rotation for longer captures has been defeated by the fantastic capabilities of Autostakert to line thing up.