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Is anyone using APT's 'Auto Cancel Exposure' function?

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I'm trying to get to grips with a few of APT's more esoteric functions.  Reading through the 152 page manual (I really should get a life!) I came across a function called Auto Cancel Exposure.  The manual describes the feature thus - "APT monitors the reported distance to the guiding star and if it becomes bigger than a defined limit the running exposure will be stopped before trails to become visible in the image, or to save imaging time for other exposure."

This strikes me a potentially very powerful tool, is anyone else using it?  If yes, how well does it work?  What would you recommend as the default auto cancel distance (the number of pixels the guide star moves before APT abandon's the exposure)?


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I'd not noticed that feature. Thanks for pointing it out.:headbang: Next time there's clear sky I'll try it out. I often reject frames with slight trailing so this would certainly save losing imaging time.

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Was able to try this out last night. Initially set to 1.0 pixel. I typically do 300s sub-frames and managed to capture a run of 10 before light cloud caused PHD to begin losing the star.  The auto-cancel in APT kicked in at 221s (labelling the image as 'Incomplete') followed by a second at 28s. At first I was a bit annoyed that APT had cancelled the first frame - it still may have been usable if it had reached 300s! Upped the pixel value to 2.0 but unfortunately was clouded out and didn't any more frames.

However, on reflection, this feature would ensure only decent sub-frames are captured and it's made me realise that I've probably been including some poorer quality sub-frames in my final stacks. I know PixInsight has a Sub-frame Selector script but this feature in APT could help maximise imaging time. Thanks @Yoddha.

Also, if PC (or card) storage is limited, using this feature will require regular monitoring since on a bad night, sub-frames could mount up considerably.

Thanks again for mentioning the feature.

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I love APT, it has never let me down.  The great thing about it is if you want a feature then just contact Yoddha and if he agrees it's a good idea he'll likely code it into the next release or two!

Edited by kirkster501
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