Capture sequence interval = exposure time + remaining time

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Jonk
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Capture sequence interval = exposure time + remaining time

Post by Jonk » Thu Nov 07, 2019 10:26 pm

I've stared using Sharpcap for an Allsky test setup, and as has previously been mentioned on here, as an alternative to AllSkEye.

AllSkEye has an option to set an interval between exposures (called 'pause'), let's say for example 60 seconds.

Running with autoexposure as the sun goes down and the light fades, the exposure time will get longer as it gets darker, as would be expected.

AllSkEye will start the pause as the exposure starts, so if the exposure was 30 seconds, there would be a 30 second pause until the next exposure.

In Sharpcap, the interval (again set to 60 seconds) only starts once the current exposure is complete.

This means that if the exposure was 60 seconds (the limit in this case), there will be a 60 second exposure then a 60 second pause before the next one starts.

This will not look correct when doing a day - night- day timelapse, as the resulting video will appear to slow down during the dark part.

Is there a way around this, as I can't see what I'm doing incorectly, if anything?

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Re: Capture sequence interval = exposure time + remaining time

Post by admin » Fri Nov 08, 2019 10:40 pm

Hi,

I think a different approach may work – set the camera to record video with no sequence and set the frame rate limit to one frame per 60 seconds and set auto exposure. The camera will take auto exposure images continuously, but SharpCap will only allow one to be saved to the output file every 60 seconds, which should give effectively the result that you are after.

Cheers, Robin

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Jonk
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Re: Capture sequence interval = exposure time + remaining time

Post by Jonk » Sun Nov 10, 2019 11:33 am

Hi Robin,

Thanks for the reply.

I actually want to save .fits files individually for editing later on (for a number of reasons, hot pixel removal / bad pixel map etc.).

Another thing I'd like to see is the preview update at max fps, but still only save the image once every minute.

This way, I can see clouds moving, trees swaying etc at any point in time (much like a cctv camera) and whilst not important really, I think looks nice.

The ulitmate goal is a 'live' view of the sky at any time, with the ability to save a .fits sequence (at 1fpm) at the press of a button, with auto gain / auto exposure up to 60secs.

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Re: Capture sequence interval = exposure time + remaining time

Post by admin » Mon Nov 11, 2019 9:07 pm

Hi,

I can't think of a way to achieve that with the functionality that SharpCap has at the moment except by using the built in python scripting tool. There are lots of posts in the scripting sub forum that discussed people putting together similar scripts to do interval based capture. If you have any experience with programming then you might find that something that be worth trying.

Cheers, Robin

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