ZWO ASI6200MM ASCOM driver cannot set gain correctly

lucam

I updated the ZWO ASI camera ASCOM driver to version 6.5.16.3 (this is what it says in the driver window, it corresponds to version 6.5.1.3 on the ZWO website) together with the corresponding native driver. The native driver works well in Sharpcap. However, when I use the ASCOM driver in Sequence Generator Pro and Sharpcap, the gain can only be set between 0 and 100. I don't know what these values correspond to in relation to the full range of gain (0 to 480) for the ZWO ASI6200MM in the native driver. Is this correct or is it a bug? If it is correct, what does gain 100 in the native driver correspond to in the ASCOM driver?

I wanted to test if an older version of the ASCOM driver worked correctly (it used to work until I updated the native and ASCOM drivers to the 12/31/2020 version). Where can I download previous versions of the drivers?

Thanks,

Luca

Tech@ZWO

Hello

Analog gain offers higher sensitivity and less noise than using only digital gain. The result: higher refresh rates, higher sensitivity and less noise.

So，0-100 is the Analog gain
100-480 is the digital gain

lucam

So if i understand correctly, gain 100 in the ASCOM driver and gain 100 in the native driver are the same operating point, corresponding to where HCG kicks in and read noise is dramatically reduced. Is this correct?

Thank you very much for the quick response!

Luca

lucam

Just to clarify, I image mostly in narrowband and want to use this camera at gain 100 where the read noise is 1.5e. If I choose gain 100 in the ASCOM driver, is this the operating point I will select?

Thanks,

Luca

Tech@ZWO

lucam

Yes,"low gain"is generally for Deep space photography（needs the long exposure）
On the opposite Planetary photography requires shorter exposure time and relatively high gain

If I choose gain 100 in the ASCOM driver, is this the operating point I will select?
Yes

lucam

Thank you!

lucam

While I understand your point about lower gain being generally preferable to higher gain and in particular that there shouldn't be a need to select a gain higher than 100 in this camera for imaging, I would make the request that the same gain selection range be available in the native and ASCOM driver. The inconsistency only creates confusion. Furthermore, for utility frames like plate solving or focusing, sometimes it is convenient to bump up the gain to keep exposures short and include enough stars. I don't see any advantage in not providing the same gain choice that the native driver offers to the user.

thanks again for the attention and responses.

Luca

Software@ZWO

ASCOM is generally used for deep sky objects. When we make DSO photography, we don't need digital gain(more than 100). The native SDK needs to consider the situation of planetary photograghy. When we make planetary photography, we may use digital gain.