Exptime limits for allsky

stempels

I'm using the SDK to develop an automated allsky meteor detection program, and this works really well for ASI cameras. Currently I'm reading the cameras in video mode at constant framerate of 10 fps, and with autoadjusted brightness/gain settings. This gives great video data for meteor analysis.

However, a framerate of 10 fps leaves me with an overexposed image during daytime.

From the SDK (and this forum) I understand that the exposure time can be automatically adjusted. I tried this, and then I do indeed get properly exposed daytime images, but at night the exposure time then goes up to very high values, tens of seconds. While this may indeed give very deep sky images, these are not useful for video meteor analysis. I'd rather use short exposure times and high gain.

Is it possible with the SDK to specify a range (or upper limit) of acceptable exposure times? Most other automatically adjusted parameters, such as gain and brightness, do have such upper limits.

Cheers,

Eric.

Sam@ZWO

yes, you can set the max exposure time limit

but the minimal is 1s exposure

stempels

Thanks. I more or less expected that it would be the AutoMaxExp parameter that is intended to control this. However, this does not work for my combination of camera (ASI185MC) and SDK (v0.3.0324). If I call this with


status = ASISetControlValue(asi_camera_id, ASI_EXPOSURE, 100000L, ASI_TRUE);
status = ASISetControlValue(asi_camera_id, ASI_AUTO_MAX_EXP, 1L, ASI_TRUE);

or

status = ASISetControlValue(asi_camera_id, ASI_EXPOSURE, 100000L, ASI_TRUE);
status = ASISetControlValue(asi_camera_id, ASI_AUTO_MAX_EXP, 1L, ASI_FALSE);

it does not have the intended effect. Instead the exposure time increases well beyond 1 second (even more than 30 seconds). Or am I missing something here?

I also notice that there is an inconsistency in the unit of exposure time here, where Exposure takes microseconds, AutoMaxExp takes seconds. That unfortunately means that it appears impossible to implement lower max-limits on exposure in the future.

Is the boolean after the max-limits such as AutoMaxExp significant?

(Another inconsistency is that GetVideoData() takes the timeout in milliseconds)

Cheers,

Eric.