ASI1600MM Cool Saturation

acab

I'm trying to determine at what point the exposure is not linear anymore. This normally happens when it starts getting close to saturation or in other words when it starts reaching the Full Well capacity. However, when does the ASI1600 saturate? The specs say the Full well is 20,000 e. This camera has a variable gain. For example:

Gain 0 is about 5 e/ADU.

Gain 139 is about 1 e/ADU.

Gain 300 is about .2 e/ADU.

Also the camera's ADC is 12 bit so the maximum ADU is 4095. However, it is expanded to 16 bits. I suppose it is multiplied by 16. Therefore, the maximum ADU downloaded from the camera is 4095X16= 65520.

So, the question really is: At gain 139 (1e/ADU) does the camera start becoming non-linear when it gets close to an ADU of 20,000 (Full Well divided by gain of 1e/ADU)? Or at 1250 (20,000/16)?

Sam@ZWO

at gain 139, 1e/ADU

the full well is 4095e

the value is 4095e*16=65520

acab

Sorry I didn't explained myself. By Full well I'm referring to the actual capacity of each photosite in the camera sensor. As I understand this would be independent of Gain or even ADC bits.

The Full Well you describe actually changes with gain? 4095 at gain 139, 20,000 at gain 0, etc.

So does ZWO uses the term full well as the maximum achievable well with gain and ADC bits?

Sam@ZWO

the real "full well" cannot be read out if you turn up gain

so the full well we talk about is changing with gain

such like in this image

acab

Thank you!

Then the camera will not became non-linear at the higher gains such as 139 or 300. Is this correct?

Sam@ZWO

acab wrote:
Thank you!

Then the camera will not became non-linear at the higher gains such as 139 or 300. Is this correct?

the camera is always linear

acab

Thank you for all your answers and patience.