×

INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

ASI Camera - Gain/Offset/x-Bit


I wonder if the community can come up with a short guide for ASI users on INDI? It seems there is lots of information out there scattered all over the place which can be confusing and frustrating for new users. A short concise guide with the settings..etc would be really great! What do you guys think?
The following user(s) said Thank You: Helge, Alan Mason
5 years 10 months ago #25899

Please Log in or Create an account to join the conversation.

  • Posts: 249
  • Thank you received: 62
on another forum I asked about suggested ASI071 Pro gain/offset settings. Reply was:
"The offset for the Pro is now fixed in firmware and cannot be changed. I have heard that it has been fixed at 50.
When I first started using my original ASI071MC I used the unity gain, but I had to use very long exposures to get histograms like I was accustomed to seeing with my DSLR using an ISO of 800-1600. After researching the gain setting on the 071 I settled on gains of 200-300 as being roughly equivalent to ISO 800 on my DSLR. I eventually adopted a gain of 200 as being standard. "
The following user(s) said Thank You: Helge, Alan Mason
5 years 10 months ago #25906

Please Log in or Create an account to join the conversation.

  • Posts: 281
  • Thank you received: 29
This is very helpful. Tonight I applied unit gain with 2 and 3 minute exposure but images turned out very dark. Also running the focuser with 4x4 binning and for instance 10 sec exposure were not satisfying. For the solver, 2x2 binning and 10 sec exposure worked ok with unity gain setting. Will use try next time higher gain values as suggested.

As regards the ASI120 cam, used as guide cam, the 50% gain and zero offset settings worked pretty well. In Internal Guider, 1.5 sec exposure seem to score good results.
Last edit: 5 years 10 months ago by Helge.
5 years 10 months ago #25908

Please Log in or Create an account to join the conversation.

  • Posts: 20
  • Thank you received: 9

I ran unity gain@-10C on my newly acquired asi071 pro two nights ago on the leo triplet. 180s exposures worked out okay. I want to try the HDR setting (0 gain) next session. Helge, I was able to autofocus using a 3.0s exposure binned 2x2 and produced almost a dozen candidate stars to select upon. I used the same settings for solving at unity. I attached a screenshot....ekos gave my images a whacky iso value that I never asked to to assign to the filename. Im using a CLS filter and fitsviewer auto'd everything

On the asi120, mine gave me so many problems with dropped frames that it was almost torture to try to get 25 frames of Leo. I am a fan of the new SEP guiding mode. It seems to measure HFR of the fov to get a better guide star. I'm eyeing the asi290mini as a viable replacement to a camera that i've flashed and fought for a while.
The following user(s) said Thank You: Helge
5 years 10 months ago #25910
Attachments:

Please Log in or Create an account to join the conversation.

  • Posts: 281
  • Thank you received: 29
Thanks a lot for sharing! Maybe the observation spot I am using for testing is too light-polluted?

When you say, fitsviewer auto‘s everything, do you mean the autostretch function is enabled? In my case it is disabled.

Could you kindly share also a screenshot with the „control“ settings of the asi drivers? Just that I can cross-check if I messed up accidentally any other parameter.
5 years 10 months ago #25911

Please Log in or Create an account to join the conversation.

  • Posts: 249
  • Thank you received: 62
It could be very useful to have a comprehensive ASI camera guide as Jasem suggested. Think I'm not good enough to write it but I can contribute with my personal experience on a specific camera (ASI071 pro).
- My setup is a 115/800 f/a 6.95 apo refractor on a HEQ5 mount.
- Added a field flattener and LP filter. No focal reducer.
- Cooling always at -10. It's a low noise camera, there's no real gain to cool it further (as to specs on ASI website, astronomy-imaging-camera.com/products/as...ameras/asi071mc-pro/).
- Tried unity gain at first, then settled on 240 gain with 300s exposures . It doesn't seem to saturate too much (see attachments for M101, M81. deepsky objects that you can easily compare with yours). Probably would change for M31 or M42.
- Ignored offset as another owner on Cloudynights says it's now fixed at 50. Not really sure about that.
- Beside gain I left all other controls to their default values.

Overall I'm satisfied with these settings but please give me your opinion, there's always a benefit in trying different approaches.
Ferrante

attachments:
- ASI071 'Control' tab from Ekos/INDI
- M81 single raw 300s exp @gain 240 + histogram
- M101 single raw 300s exp @gain 240 + histogram
- M101 single debayered 300s exp @gain 240
5 years 10 months ago #25915
Attachments:

Please Log in or Create an account to join the conversation.

  • Posts: 424
  • Thank you received: 66

Replied by Greg on topic ASI Camera - Gain/Offset/x-Bit

I’m writing a guide on exposure and there are a couple of goals you can strive for in your settings. I won’t explain why for now as it will be in the guide.

One is to place the sky background peak at 2.2% of the full scale on a linear histogram like in fits viewer.

The second is to set your camera ISO/gain such that you have 11 stops/64 dB of SNR.

With regards to offset, I don’t see this as an important factor as any image will only have usable content above the background level, which is to be set at 2.2% as mentioned. So 0 offset is probably fine.
5 years 10 months ago #25921

Please Log in or Create an account to join the conversation.

  • Posts: 39
  • Thank you received: 11
Are the sensors really that uniform, one could take the values from others? I took biases with the qhy168 I got from a mate for gain 0, 5, 9, 11, 12, 13 ,14. For each gain set, I watched the histogram of the bias and adjusted the offset value, so that nothing of the left "foot" of the histogram was clipped to black.
The higher gain came, the higher the offset was to be set not to clip anything on the left side. The resulting offset/gain table was not linear in this case. I think in principal this should work the same way with any cmos cam.
These offset values then should be applied to all light and calibration frames of course.
What I don't understand is: why do manufacturers not normalize their setting to 0-100%, so every cam has different max gain settings now?

Andreas
5 years 10 months ago #25922

Please Log in or Create an account to join the conversation.

  • Posts: 39
  • Thank you received: 11
@ gbeaton:
I think this is a misconception. Calibration frames like bias or darks might be clipped on the left side of the histogram with offset 0. This could introduce artifacts during calibration.
jonrista.com/the-astrophotographers-guid...oise-and-histograms/
scroll down to "Anatomy of Signals in Histograms". The offset value prevents the "separation" of beeing negative.
Andreas
Last edit: 5 years 10 months ago by Andreas.
5 years 10 months ago #25924

Please Log in or Create an account to join the conversation.

  • Posts: 424
  • Thank you received: 66

Replied by Greg on topic ASI Camera - Gain/Offset/x-Bit


Yes, you could be right. I forgot to mentioned that as far as offset goes, I haven't studied it.
5 years 10 months ago #25930

Please Log in or Create an account to join the conversation.

  • Posts: 20
  • Thank you received: 9

Helge,

Yes, I set kstars fitsviewer settings to include autostretch and occasionally debayer as was in that image. I included my settings page for both cameras. I hope you have better luck with the camera.

WHERE is everyone getting this gain of 50 for HDR on the asi cooled cmos cameras? I keep seeing post with that value included but it's not what Sam at ZWO states as Highest Dynamic Range (widest range of signal that the sensor can record) Cooled ASI Camera Settings
The following user(s) said Thank You: Helge
5 years 10 months ago #25957
Attachments:

Please Log in or Create an account to join the conversation.

  • Posts: 424
  • Thank you received: 66

Replied by Greg on topic ASI Camera - Gain/Offset/x-Bit


It’s not camera dynamic range you are trying to achieve. It’s star SNR. If you have high gain the bright stars with high SNR will be saturated. These are all trade offs of course so it’s also related to exposure time. Because you probably have to have longer exposures for guiding to smooth things out. You’ll have to turn down the gain. You can corroborate what I’m saying with PHD2 “best practices”
5 years 10 months ago #25958

Please Log in or Create an account to join the conversation.

Time to create page: 0.969 seconds