Exposure times may be wrongly measured

The equipment for this operation: C11 Edge with DSLR Canon 5D mk2. Camera settings believed correct for long exposures. I have been taking multiple 1 minute images and hear a sound sequence every time that I believe is wrong. At the start of the exposure I hear the loud mirror lockup and then after a few seconds (set to allow vibration dissipation), the shutter opens. However, SGP starts the countdown from mirror - not actual exposure. I suspect that the exposure times listed are therefore wrong. I also hear what seems to be an anomalous end (click before shutter close) and again the timer seems to continue until the last click. It maybe that I am interpreting the sounds wrongly - I can’t be sure.

Lawrence Harris

The exposure timer that is displayed does not take the mirror lock up into account and starts counting down as soon as an exposure is requested (which is what fires the mirror lockukp)…but the actual camera exposure does take this into account so the display is incorrect but the actual exposure length is not. We can look into addressing the actual display.

Thank you,
Jared

Hello Jared

Actually there is more to it than that. I have a delay of 6 sec set
after ‘exposure start’ (t allow for vibration) and I hear this delay,
but the SGP timing does not apparently allow for that because I see it
counting down despite the pause being acknowledged. Its not exactly
critical but its seems worth my pointing it out. The FITS header appears
therefore wrong. Again of course I may understand this wrongly.

regards

Lawrence

Where are you setting this delay?

Thanks,
Jared

Equipment profile manager/camera settings/mirror settle time

FWIW I now have the evidence. Last night using 60 sec exposures in
sequence, I saw the camera announce 30 sec exposure at 1600 ISO
(correct) and then do a dark subtraction that was switched off in the
camera menu. I had had and interpreted correctly. The curious thing is
that these images were better than the subsequent 60 sec images that
happened after I had powered the camera off and done a reset! I have yet
to check all the results.

Thanks

Lawrence