Some notes on setting the Seestar gain values

High vs Low Conversion Gain modes (HCG vs LCG)

from seestarpy import raw
raw.set_control_value(gain=80)

According to the docs on the IMX462 chip, it has two internal capacitors which are used to read the pixel values. The larger capacitor used in the LCG mode can map the full pixel well depth of 32k electrons, albeit still only with the 12-bit ADC. The smaller, more sensitive capacitor used for the HCG mode, can only map to about a third of the full well depth. However this small capacitor produces less noise and is therefore much better suited for low-flux objects such as nebula and galaxies.

Use cases:

• If you prefer to map the full dynamic range of as many stars in the field as possible, without the bright ones “burning out” (i.e. saturating) then it makes sense to use the LCG mode, with gains set to below 80

• If you are looking for the best possible contrast within extended sources like nebulae and galaxy disks, then the HCG mode is better suited. Set the gain value to 80+