Sharpcap sequence calibration preprocessing issue

[TimAldworth]

I have run an automated 'Test' SharpCap sequence that performs the following [All captures are around 4 seconds, as is the MasterDark]:
1. 100 x captures with No Calibration Pre-processing.
2. 100 x captures with Only Flat Calibration Pre-processing.
3. 100 x captures with Only Dark Calibration Pre-processing.
4. 100 x captures with both Flat& Dark Calibration Pre-processing.

The 'Blocking' issue only occurs sporadically [20 to 30%] in cases '3' and '4' above, ie when 'Dark' Calibrations are applied, but importantly, not on the same frames in the run, indicating, to me, it is not the dark frame responsible, as the same single Dark Master File is used for all 100 x captured light frames.

My laptop is a recent model, bought 8 months ago, so would expect the processor to be fairly up to the job:
Processor: i5-1240P CPU [1700MHz]
Installed RAM: 8.00 GB LPDDR5
S/No: R9N0LP03H38439H
Model No: UX3402ZA - KP234W
P/No: 90NB0WC1 - M00JU0
MAC No: E0C2644C9582
MS Product Key: 3422112532947
System type: 64-bit operating system, x64-based processor

What I have now done is to use the same [Uncalibrated] Light files and [Dark and Flat] Cal files to apply calibrations in another 3rd party application, AstroPixelProcessor. This post processing appeared to work well with 100% good calibrated light files.

[admin]

Hi,

yes, the 1240p processor looks like it should be up to coping with that sort of workload without a problem, although it may be worth checking the Windows power saving settings, just in case it is set to keep the processor speed too low for power efficiency.

Other than that, there's not much to suggest except continued experimentation if you want to get to the bottom of this - try a different PC, try smaller ROI and other things - if you can find one or more things that affect the problem then we have a bit more info to go on.

cheers,

Robin

[TimAldworth]

Hi Robin

My bad I'm afraid! I use a Pegasus Pocket Powerbox to supply:
1. ASI533MM-Pro [Cooled] + EFW + ASI120MM [OAG Guide camera].
2. Sesto Senso focuser.
3. iOptron IEQ45 mount.
4. USB Hub.
I have just tested the Current/Voltages and, not surprisingly, my 12V/10.83A Power Supply [PowerPax SW3477D], powered from the mains [240VAC], looks to be right on the threshold of it's capacity, and failing to regulate the output voltage to 12V, measuring 11.3v input to the PPB on occasions.
I now will upgrade to a better 12V/10A Power Supply!

Other forums have listed similar issues with ZWOASI533 cameras and the 'blocking' issue that I experienced. Most, if not all, fixed by improving the power supply.

[admin]

Hi,

glad you found the cause, hopefully a new power supply (or a separate one for one of the bits of equipment) will resolve the issue. Still not quite sure how the PC being busy (applying processing to the images) would affect it, unless the PC is also running off of the 12V power supply and the busy processor (high power draw) causes the voltage to drop...

cheers,

Robin

[TimAldworth]

Not convinced it is the Power Supply!
The test is conducted with my standard imaging rig with a Pegasus flatpanel set to 50% illumination in a lightproof cowl over the telescope.
In both variations of power supply, the SharpCap histogram shows an intermittent jitter, where the mono response jumps by about 2-5% on the 'X' axis [eg 47% to 52%], then back again, maybe 4-6 times over a minute. This I thought I would investigate.
First test to isolate the camera 12V power from the mount/focuser/USB hub supply:
I have powered up the ZWO ASI533MM-Pro + ASI120MM + EFW with a separate LiPo Hi capacity battery [Tracer 12V 8Ah Lithium Polymer Battery Pack].
This draws around 0.8A, at 12.2V, with around 60% cooling power to reach an arbitary target of -10 DegC.

I then monitored the histogram behavior to see the 'jitter'. Attempted to attach a screen video grab [~900kb] illustrating [52% to 53% to 52% histogram value], but would not allow .mp4 or .mov formats, is there a method to do so?

[admin]

Hi,

the forum has a limit on attachment size of 1Mb anyway, so that would likely block you even if the file formats were allows. For larger files (including videos), it's usually best to find somewhere to share them from (Google Drive, OneDrive, even YouTube for videos - whatever works for you) and then post a link to download/view the files here on the forums.

It would be worth checking to see if the jumps in histogram remain when using a different light source - daylight or indoor lights or something. That would ensure that glitches in the flat panel brightness are fully rules out.

cheers,

Robin