Missing file capture using "Sharpcap Configure Capture"

Discussion of using SharpCap for Deep Sky Imaging
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stbkaiser
Posts: 158
Joined: Wed Aug 15, 2018 2:57 pm

Missing file capture using "Sharpcap Configure Capture"

#1

Post by stbkaiser »

I had some unexpected results after Setting up a "Sharpcap Configure Capture" procedure
1. At 00_14_58 two pictures were captured for the same time stamp when only 1 image should be captured

2 At the following time stamps NO image was recorded even though a sub directory was created by SC for the time stamp.

00_19_26
00_23_30
00_30_38
00_39_10
00_46_17
===================================
see log file
Log_2024-06-24T22_47_50-10144.log
---------------------------------------------
System setup
Computer system
Mele Quieter 3C ,
Quad Core N5105 Processor 2.00GHz
Win 11 pro 64 bit
250 gb SSD main drive, 1 tb SSD secondary drive (files captured here)
8 gig Ram
Camera-lens
ZWO-ASI385MC camera with ZWO 150º CS Lens on tripod.
SharpCapInstall-4.1.12221.0-64bit


SC Setup "Sharpcap Configure Capture"
Capture fits label is M42

Initially:
SC capture set to capture "time Limit" 20 sec Fits image every 1.5 min for "Sequence Length "100 captures
I ran SC for 8-10 captures
--------------------------------------

then at 00:20:43.965901 I stopped the capture sequence
changed "Sequence Length "to 20 captures
restarted captures

====================================
Any ideas why SC did 2 captures one time and no captures for multiple exposures?

Thanks
Steve
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Re: Missing file capture using "Sharpcap Configure Capture"

#2

Post by admin »

Hi,

the missing captures are fairly easy - from the log I can see that the captures were run in time limited mode with a limit of 25s. It looks like the exposure was set to 30s, so depending on the exact relative timings of the frames arrriving from the camera and the capture window of 25s, you may or may not get an image captured (about 5/6ths chance of getting one). It's best to use frame limited captures when using longer exposures rather than time limited (which are best for short exposure video style captures).

Actually, a deeper look at the log also reveals the cause of the double image capture - at that point you were running exposures of 19.876s, so there is a chance that 2 images will arrive in a 25 second window, again depending on the exact timing of the exposures arriving.

Remember that when SharpCap runs the camera in 'Live Mode', the camera continually captures frames and the rest of the operation of the program deals with those frames when they arrive. You can get exact control over when frames are captured by putting SharpCap into still mode if you want, but that brings its own tradeoffs.

cheers,

Robin
stbkaiser
Posts: 158
Joined: Wed Aug 15, 2018 2:57 pm

Re: Missing file capture using "Sharpcap Configure Capture"

#3

Post by stbkaiser »

OK I think I see what I mis interpreted.
The Exposure "time Length" for CONFIGURE CAPTURE panel is controlled via the setting in the CAMERA CONTROLS panel.
I t was getting late that night and the bugs were really distracting. :roll:
I was thinking the TIME LIMIT setting was the exposure time. ;)
thanks for clarifying.
take care
Steve
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