Gain is too high on luminance shots - but fine on Red green and blue - how to adjust?

So getting back into astro photography - I run several cameras simultaneously on 3 scopes - with SGP controlling my ZWO 1600MM-c and ZWO filter wheel and focuser on a Williams Optics 132mm refractor.

Side by side APT manages a ZWO 071MC-C to a Moonlight focuser to a Williams Optics 115mm scope.

So in APT I set the binning, gain, exposure etc… But in SGP I gather the Gain is detected by the camera driver on camera connect and it applies to all frames taken in an event sequence.

Last night I was doing a test / calibration run on NGC 5139. The camera driver defaulted to Gain of 240. I was shooting a sequence of 10 x (Luminance, Red, Green and Blue frames) - each of 2 minutes duration, each binned 1x1 each rotated through one at a time. The Red, Green and Blue frames all came out fine - I had no issues registering and stacking each seperately in 3 runs of DeepSkyStacker 64 bit. The Luminance frames were way too blown out - I presume a 240 gain on a 120 second shot on the 1600MM-c is way too high.

Is there a way I can run a sequce like this - but set different gain for different filters (through event options or something for the Luminance frames)?

I don’t want to have to disconnect the camera and reconnect it with a different gain each time I wish to shoot Luminance frames. Similiarily when I shot narrowband frames I might wish to change the gain too.

Appreciate any help that can be offered - on the optimal gain for a target like NGC 5139 on a ZWO 1600MM-c and how to set lower Gain for just the Luminance shots on the sequence!

One other wierd behaviour - for all the colour filter light frames - the camera name was inserted for the file name, but for the Luminance frame no camera name appeared…

The Event Name was 5139 - and I set the suffix to be the same too

The file name selected was the same for all - %ft%tn_%el_%fe_%bi_%su_%04 so wondering why my files were names:

NGC 5139_120sec_Green_1x1_NGC 5139 Green 1600MM_0007 or
NGC 5139_120sec_Red_1x1_NGC 5139 Red 1600MM_0005 or
NGC 5139_120sec_Blue_1x1_NGC 5139 Blue 1600MM_0004 vs

NGC 5139_120sec_Luminance_1x1_NGC 5139_0002

If the clouds go away I will try the 64 bit version and determine its behaviour too!

Useful Info

OS: Windows 10 Pro
Ver: SGP

When setting up your events if you click on the little “gear” icon it will open parameters for that event, one option is “event gain” and you can adjust it there. One thing to note though, It will set the gain in the driver so any events after will remain at that gain. You will need to specify the gain in the next even if you want it different for the remaining events. Again, the gain will be set in the driver from the last event so even after restarting the computer, it will remain at whatever the last gain setting was set to.

There are 3 places to set the gain.

  1. the camera driver
  2. in equipment profile
  3. event parameters.
    If you set the gain in the equipment profile, it will override the driver gain and if you set the gain in the event, it will override the equipment profile gain.

An option is, if you want the RGB gains all the same set that gain in the equipment profile (under the camera tab) then you should only have to change the gain in the events for the luminance filter and it should default back to the RGB gain for any event after if you don’t specify in the other events.

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Many thanks - have set that up to do two luminance runs - one at gain 0 offset 50 and one at gain 100 offset 50, followed by Red, Gren Blue at gain 240 offset 50.

I picked the offset from the ZWO driver itset - for low medium and high gain settings for this camera - all the offsets (under teh advanced tab) were defaulted to offset 50.

Will report how it goes - many thanks for the prompt and detailed response!

Good luck. I hope I didn’t confuse you too much with the explanation.

Unlike tonight’s skies - your explanation was crystal clear!

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Worked fine many thanks!

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That’s great. I’m glad it worked out for you.

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