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The other night, I got a rather weird thing happen using Sharpcap. In live-stacking, the first image arrived and it was full of stars. So, without changing any settings, I did a "platesolve" (which also realigns the scope) to centralise my target. It did its single frame capture and I got a practically blank screen and a message saying it could only detect 3 stars. I tried reducing the "sigma" setting, as advised by the on-screen message, with little effect. What gets me is that the same settings produced a whole mass of stars in each of the subs that were being live-stacked. Never had this happen to me before, and no, of course I didn't do anything intelligent like saving the log file!
I can always try to replicate this next time (although I always find trying to replicate something that isn't working to be a weird activity in itself!), but on the off-chance that anyone can see what was happening without the log file, I thought I would ask.
This is Markarian's Chain shot from my back garden over three nights in late March. Probably the deepest single image I've taken in terms of integration time...which leaves me feeling my processing is not quite doing the data justice...maybe I'll come back to it.
In any case, this is an incredible part of space; looking away from our galaxy reveals countless others!
The crazy number of Lum subs took a whole day for APP to chug through and so I've resolved to lower the gain from unity going forwards to get more manageable sub lengths than 15 seconds!
L: 1050 (!) x 15s R: 92 x 60s G: 165 x 30s B 165 x 30s....total integration time 8.2 hours.
Captured using APT, stacked in APP and processed in Pixinsight.
Thanks for looking!
Edit: Link to higher res version
I am starting to get to grips with some of the features on Sharpcap and last time out I tried to use the focussing assistant using a bahtinov mask.
The first thing I noticed is how sensitive it is. The attached screenprint involved the tiniest movements of the fine focusser knob on my Star71, which caused it to sweep from +1 to -1 without stopping in the middle. I decided I wasn't going to do any better than that (but could probably waste an awful lot of clear-sky-time trying!), so decided to accept that. After all, from what I have read, an FWHM of about 1 is reasonable.
But now comes my confusion. I was assuming that the scale was FWHM units. But, as can be seen from the screenprint of the log, the FWHM of each individual sub was just under 4. I realise it would not necessarily be the exact same figure as when I was focussing, but 4x that figure? This would seem to suggest that either the scale on the focussing assistant is not FWHM units (so what is it?), or my focussing went way out during my imaging session. The resultant image can be seen here.
So, are these the sort of results I should be expecting? Or where am I going wrong?
Outside there is something coming out of the sky that strongly resembles the Atlantic Ocean being poured through a seive, so I thought I would give the 'sensor analysis' option in sharpcap a go on one of my cameras. This resulted in the table attached.
I'm sure all the figures are great, but as to helping me decide which gain setting I should use for this camera, I am not a lot wiser. There definitely seems to be something strange (impressive?) happening to the read noise between 60 & 61, but it continues to decline after that so I'm not sure that gets me very far.
So, it's time to get educated ... (1) which is my best option, and (2) why?
224 sensor analysis.txt
I have recently purchased a ZWO ASI120MC-S webcam from FLO. I wanted to try it the other night so I decided to get some test images for the moon. I was using Sharpcap for this. I manged to get the video and was using Autostakkert to stack it. On the final stacked image I can see that there are some strange vertical lines. I have attached a picture of that. There is also a zoomed in image of a region and I can see some small squares almost resembling the pixels on the sensor. Below are my capture settings as given by SharpCap.
[ZWO ASI120MC-S] Debayer Preview=On Pan=0 Tilt=0 Output Format=AVI files (*.avi) Binning=1 Capture Area=1280x960 Colour Space=RAW8 Temperature=19.2 High Speed Mode=Off Overclock=0 Turbo USB=86(Auto) Flip=Both Frame Rate Limit=60 fps Gain=50(Auto) Exposure=0.001993 Timestamp Frames=Off White Bal (B)=95 White Bal (R)=52 Brightness=0 Auto Exp Max Gain=50 Auto Exp Max Exp M S=30000 Auto Exp Target Brightness=100 Mono Bin=Off Apply Flat=None Subtract Dark=None #Black Point Display Black Point=0 #MidTone Point Display MidTone Point=0.5 #White Point Display White Point=1 TimeStamp=2018-06-25T23:13:22.6772909Z SharpCapVersion=3.1.5214.0 For Autostakkert (v2.6.8 ) I was not doing anything fancy. Pressed analyze and then used 50% of the frames to stack. Used 200 as the AP size. Also, had the drizzle as 1.5x
My camera was mounted to a skywatcher 200pds and HEQ5 mount.
I am failing to understand what is going wrong here. Is the camera a problem or stacking is an issue ? Please let me know if there is any more information that you need.
Thanks and Regards,