ZWO ASI178MC Gain/Offset Combinations

13 Feb, 2018 09:52
Hi @strobin,

I tried my luck at the official ZWO-Forums, but didn't get a response until now, and tonight will be clear skies at my location, so i wonder if here is anybody who can give me an advice about this topic:

After more than half a year using the great ASI178MC with several combinations of Gain/Offset, i thought it would be a good idea to stick to only a few standard combinations. So after reading through many posts in several forums i'd like to discuss if these combinations do make sense or if i need to adjust them (the numbers represent the settings in SharpCap, where Gain=Gain and Offset=Brightness):
  • LOW: G 85 O 75
  • MEDIUM: G 128 O 300
  • HIGH: G 192 O 400
  • ULTRA: G 380 O 400
Any ideas about these settings? Good or bad? Are you using similar settings or are yours completely different?
Thanks in advance for any advice!

Clear Skies,
Edited 13 Feb, 2018 10:08
13 Feb, 2018 20:51
Okay, forget what i've written. These settings don't work :-(
19 Feb, 2018 16:39
I have also been searching for the same information for the ASI178mc and have found very little until recently.  Check this link from the camera manufacturer’s website:

The mini article is about the ASI1600 and ASI071 gain settings however the 3rd question down from a customer (Nicolas) asks about gain settings for the ASI178mc.  ZWO Founder, Sam Wen, says to use the gain settings listed in the ASCOM driver for the ASI178mc.  When I checked the ASCOM settings using SGPro here is what I found:

Unity Gain ==>    Gain: 180   Offset: 25
Highest Dynamic Range ==>   Gain:  0    Offset:  25
Lowest Read Noise ==>   Gain: 270   Offset:  340

I also sought some guidance from the very helpful folks at out of Seattle where I’ve bought most of my telescope equipment and they generally recommended using a gain of around 50-100 for DSO and a higher gain, perhaps ~300+ for brighter planetary targets.Up to this point I have been experimenting with gains in the 250-330 range using short exposures, unguided.  My results are fairly mixed so far.  I live in an area with a lot of light pollution which tends to dominate my photos.  I am awaiting the arrival of a guide camera and scope along with a light pollution filter this week and I intend to try these recommended settings at my first opportunity.
Hope this helps,
Edited 19 Feb, 2018 16:42
19 Feb, 2018 19:12
Hi Joe,

thanks fpr your reply. I played around recently with SharpCap (native drivers, no ASCOM) and the gain/offset settings. Whenever i touch the brightness value (which i believe to be offset)  the images are way too oversaturated - just white. Maybe i am doing something wrong, but at the moment i leave the brightness value at zero.

I am using gains between 64 and 256 depending on the target. I tried short exposures, but then i could not align the images due to too less stars in the field of view. At the moment i try to reduce the differential flexure on my autoguiding setup (see ). When this is fixed i'll come back to the problem with gain/offset combinations.

Nevertheless i am happy for your reply and wish you good luck with your new equipment.

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