On a related topic any opinions on Offset and Gain? I will be using a 90mm f/5.6 scope and L-eNhance filter in the city and no filters at my dark-sky site.
Dr. Q of QHY has a write up about gain and offset calculation here:
The other resource you should use are the graphs that ZWO published for the camera:
Scroll down to the line graphs under "Camera Performance". You will want to key in the bottom 2 of the 4 graphs they have:
Unique to this sensor and a few others (IMX455, IMX294) there is a dual-gain mode; high and low. Note that on a typical CMOS sensor, dynamic range (DR) of the sensor drops as gain increases. Read noise decreases. On this sensor, once you turn the gain up past a certain point, the camera switches to a high gain mode where the read noise drops and dynamic range is mostly recovered. This is pretty much a sweet spot of the camera: you get the most DR for the least read noise. For standard DSO astrophotography, you will want to start at this point. So I would guess, start at a gain value of 100, while following Dr. Q's instructions of determining your offset.