ASI120MM-S Minimum exposure and donwload time

Julio939

Hello.
We are a group of amateur astronomers dedicated to meteor observation. Our stations are made up of an ASI120MM-S camera and a Raspberry 4-B, running our own production software. We have observed different behavior on some cameras:

Experimenting with the minimum possible exposure time, for daytime observation, we have observed that in some cameras (1) the real minimum time is about 180 us, and that this time can be increased later in steps of 90 us. In other cameras of the same model (2) these times are half: 90 us minimum with increments of 45 us.
On the other hand, analyzing the download time with:
ASISetControlValue(CameraId, ASI_BANDWIDTHOVERLOAD, 100, ASI_FALSE);
ASISetControlValue(CameraId, ASI_EXPOSURE, 0, ASI_FALSE);
We also observe differences between the two cameras. Those of group (1) download an image in binning=1 in 32 ms, while those of group (2) do so in 16 ms. All cameras run with the same configuration and the same software.
We would like to know the reason for this difference, and if the slower cameras can be corrected, for example with a firmware update.
Thank you very much and best regards.

Software@ZWO

Julio939
Hi Julio,
(1) Please exchange the USB data cable and the USB port on the raspberry pie to see whether the phenomenon follows the camera, the USB cable or the USB port.
(2) If you finally verify that the phenomenon follows the camera, we'd like you to send us the SN of the "fast" camera and the SN of the "slow" camera. We need to further check the problem.
Best Regards