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Asi 1600mm pro GAIN

ZWO ASI1600MM COOL CMOS Acquisition Narrowband Deep Sky
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Daniel Renner avatar
Daniel Renner avatar
When I started imaging with my ASI 1600 mm pro I always used Unity gain (139) and offset 50. But recently I have read threads of doing 200 for NB and 75/76 for rgb stars so I have also tried this approach. And I use unity gain for broadband targets.

I usually go for 300s on NB and around 120-180 on broadband, depending on how much im clipping.  Do you think this is a good approach? or should I change anything?
(I live in a borte 5-6 zone)

Also some people using gain 76 and some use gain 75, does that really matter?
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Andy Wray avatar
Andy Wray avatar
I've just used unity gain across the board and then adjusted the exposure times to hit a target ADU.  The only other gain I use is gain 0 for the flats as my LED flat panel (even at its lowest setting) is too bright at unity gain with two t-shirts.
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Daniel Renner avatar
Daniel Renner avatar
Andy Wray:
I've just used unity gain across the board and then adjusted the exposure times to hit a target ADU.  The only other gain I use is gain 0 for the flats as my LED flat panel (even at its lowest setting) is too bright at unity gain with two t-shirts.

*** doesn't the gain need to be the same as your lights? ***
Andy Wray avatar
Andy Wray avatar
Daniel Renner:
Andy Wray:
I've just used unity gain across the board and then adjusted the exposure times to hit a target ADU.  The only other gain I use is gain 0 for the flats as my LED flat panel (even at its lowest setting) is too bright at unity gain with two t-shirts.

*** doesn't the gain need to be the same as your lights? ***

I don't believe so as flats are a division rather than a subtraction function ... darks and flat darks definitely have to be at the same gain and offset as their respective lights and flats.
James avatar
James avatar
I use a 1600mm in a bortle 5 and have been using gain 76 for broadband and gain 139 for narrow band.  I selected those values because it seemed to be the values other folks with very nice images are using.   Its been working for me.  On exposure.. depending on the target,  lum is anywhere from 120 to 180".  RGB is 180-240".  Narrowband I use 600".
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Dan H. M. avatar
Dan H. M. avatar
I don't see any reason to use anything higher than gain 0 for LRGB on the ASI1600.  The ASI1600's base read noise is 3.5 e-, which is extremely low.  My personal suspicion is that the "Gain 76" advice came about because people were obsessively trying to reach minimal read noise when the camera was still new.  Now everyone is using CMOS cameras and experienced imagers regularly take 3.5 e- read noise or higher to take advantage of the higher FWC.
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Vaughan avatar
Vaughan avatar
I don't see any reason to use anything higher than gain 0 for LRGB on the ASI1600.  The ASI1600's base read noise is 3.5 e-, which is extremely low.  My personal suspicion is that the "Gain 76" advice came about because people were obsessively trying to reach minimal read noise when the camera was still new.  Now everyone is using CMOS cameras and experienced imagers regularly take 3.5 e- read noise or higher to take advantage of the higher FWC.

Very interesting and I had not considered this.  For the past two years I have been using Gain 0 for LRGB and NB.  My LRGB images were good with low noise and decent SNR, such that I have great Cluster images.  However, my NB images were lack lustre.
I've recently switched to Gain 139 (Unity).  Now, the NB are great, but LRGB are suffering, because I've had to reduce the exposure time to compensate for the added sensor sensitivity.
So, my take-away here is LRGB at Gain 0, NB at Gain 139.  Does that sound right?
Although I've been doing this for two years, I still consider myself as a beginner and still on the steep side of the learning curve   BTW my ASI1600MM Pro is through my SkyWatcher Esprit 100ED, which I find is a great match - maybe not the best, but certainly ideal for me.
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Dan H. M. avatar
Dan H. M. avatar
Vaughan:
I don't see any reason to use anything higher than gain 0 for LRGB on the ASI1600.  The ASI1600's base read noise is 3.5 e-, which is extremely low.  My personal suspicion is that the "Gain 76" advice came about because people were obsessively trying to reach minimal read noise when the camera was still new.  Now everyone is using CMOS cameras and experienced imagers regularly take 3.5 e- read noise or higher to take advantage of the higher FWC.

Very interesting and I had not considered this.  For the past two years I have been using Gain 0 for LRGB and NB.  My LRGB images were good with low noise and decent SNR, such that I have great Cluster images.  However, my NB images were lack lustre.
I've recently switched to Gain 139 (Unity).  Now, the NB are great, but LRGB are suffering, because I've had to reduce the exposure time to compensate for the added sensor sensitivity.
So, my take-away here is LRGB at Gain 0, NB at Gain 139.  Does that sound right?
Although I've been doing this for two years, I still consider myself as a beginner and still on the steep side of the learning curve   BTW my ASI1600MM Pro is through my SkyWatcher Esprit 100ED, which I find is a great match - maybe not the best, but certainly ideal for me.

0 for LRGB and 139 for NB definitely sound right.  NB gain can probably be tweaked a bit but 139 should be perfectly adequate.