Best Analogue Gain Setting For Jupiter Imaging

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morayskies
Posts: 1
Joined: Mon May 15, 2017 1:30 pm

Best Analogue Gain Setting For Jupiter Imaging

Post by morayskies » Mon May 15, 2017 2:00 pm

Hi All

Quick question. Just wondering what Analogue Gain setting SharpCap users are using when imaging Jupiter? I use a Celestron 6" SCT with a Meade 3x Barlow and GP-CAM colour (v1). With my ageing laptop, I can get between 25-30 fps at 640 x 480 resolution using 30ms exposures with an analogue gain of about 150. This is the sort of result I get with best 20% of 4000 frames after using PIPP, AutoStakkert and Registax.

Does anyone else use this setup and, if so, what SharpCap settings do you use? (PS Seeing wasn't brilliant the night this was taken). The version of SharpCap I'm using is 2.9.3032.

Thanks for looking :D
Attachments
22_20_11_pipp_AS_p20_g3_ap29_proc.png
22_20_11_pipp_AS_p20_g3_ap29_proc.png (35.82 KiB) Viewed 212 times
Clear Skies

Richard
Celestron 6" SCT, SW ED80, SW 6" f8 "Newt", SW 90mm f10 refractor

turfpit
Posts: 29
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Best Analogue Gain Setting For Jupiter Imaging

Post by turfpit » Mon May 15, 2017 7:24 pm

Richard

I have been working on this in the last few days. I have a GPCAM MONO V1 and Celestron C8. I have this produced as best 10% of 500 frames, stacked in Autostakkert and processed with Registax. Colour Space was MONO12 with a 2x Barlow fitted.
00_45_17_g8_ap13.png
00_45_17_g8_ap13.png (20.87 KiB) Viewed 202 times
This is the SharpCap 3 histogram during the capture.
SC-histogram.PNG
SC-histogram.PNG (13.39 KiB) Viewed 202 times
Method for capture was:
  • Set the gain to 70%
  • Start the histogram and ensure Logarithmic checked
  • Adjust exposure until right-hand side of histogram at 80%
  • Capture frames
  • Check the capture with PIPP SER Player, with histogram selected (ensures good data captured)
  • Repeat above steps
In Registax, I processed with Dyadic and Gaussian set, using layers 2, 1, 3 in that order.

A document detailing all steps in SharpCap, Autostakkert & Registax will be available 'real soon now'.

I would be interested in having a shot at processing your TIF output from Autostakkert if you can post it.

Exposure setting was high because I had a 685nm IR Pass Filter inline and am now keen to repeat this without the filter in order to get a better frame rate.

Background for the histogram stuff at http://docs.sharpcap.co.uk/2.9/#The%20Histogram - a shameless plug ;)

Dave

[GPCAMMT9M034M]
Output Format=SER file (*.ser)
Capture Area=640x480
Binning=1x1
Pan=320
Tilt=240
Colour Space=MONO12
Black Level=0
USB Speed=4
Auto Exp Target=120
Frame Rate Limit=Maximum
Analogue Gain=700
Exposure=214.39
Timestamp Frames=Off
Apply Flat=None
Subtract Dark=None
Display Brightness=1
Display Contrast=1
Display Gamma=1

cuivenion
Posts: 39
Joined: Wed Feb 15, 2017 7:37 pm

Re: Best Analogue Gain Setting For Jupiter Imaging

Post by cuivenion » Tue May 16, 2017 9:50 am

Hi, I also find that a high histogram is good with Jupiter. I aim for between 80-90%. I think the best way to go about it is to have your gain set to maximum and then reduce the exposure until the frame frame rate stops increasing. Then reduce the gain until you get to the required point on the histogram.

Of course you might end up with maximum gain but thats not a problem if you get enough frames. This is my best effort with the colour GPCAM V1. 2 minute capture. Best 50% of 3875 frames. Max gain, exposure 30.966ms. I used a Skywatcher 200p with a 5x barlow (5000mm focal length).
w1 Final.jpg
w1 Final.jpg (126.71 KiB) Viewed 192 times


Annoyingly I forgot too increase the usb speed or I could have got more frames. Also don't be afraid to stack more frames if they're good enough quality.

[GPCAMAR0130C]
Debayer Preview=On
Output Format=AVI files (*.avi)
Capture Area=640x480
Binning=1x1
Pan=320
Tilt=240
Colour Space=RAW8
Black Level=3
USB Speed=2
Auto Exp Target=120
Frame Rate Limit=Maximum
Analogue Gain=1000
Exposure=30.966
Timestamp Frames=Off
Apply Flat=None
Subtract Dark=None
Display Brightness=1
Display Contrast=1
Display Gamma=1

turfpit
Posts: 29
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Best Analogue Gain Setting For Jupiter Imaging

Post by turfpit » Tue May 16, 2017 9:54 pm

As promised, the document detailing all steps in SharpCap, Autostakkert & Registax is now available at http://docs.sharpcap.co.uk/howtos/jupiter/.

The document explains how to get from
1.png
1.png (12.51 KiB) Viewed 182 times
to
2.png
2.png (19.9 KiB) Viewed 182 times
via SharpCap => AutoStakkert => Registax

I used a 685nm IR pass filter and did not turn up the gain to allow for this - hence the longer exposure led to the low fps. It is all a learning curve.

I will repeat the exercise (including document) with Saturn when it stops raining here.

Dave

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