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Weird ... same settings, vastly different number of stars

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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.


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