SharpCap Forums

Very new to AP. This will be the first time I’ll be using darks and have started to try to put together a dark library. I was doing fine until this morning. I was attempting to make a dark (190 gain; 240 second exposure; brightness 12). However, each 4 minute frame was dropped and I was unable to capture this dark for my library. What’s even more confusing, is that yesterday I was able to capture a few darks at 5 minute exposure with various gains. Also, FYI: shorter exposures were no problem, just this 4 minute one. The histogram peak was off the left vertical.

Also: I was guessing about the brightness level, but as mentioned the histogram peak was hugging, but clearly off the left axis

My question: why would dark capture drop frames?

Confused
Joe

Hi,

what camera were you using and is your SharpCap version up to date?

I do recall a bug a while back with a certain model of Altair camera that would fail to take images at particular exposure lengths (I think 60s was a problem from memory). I'm wondering if it could be something like that.

Certainly, capturing a dark should not affect the normal flow of frame through the camera - therefore if you had problems with 240s exposures for a dark, I would expect you to see problems with standard 240s exposures too.

cheers,

Robin

Hi Robin,

I'm using a ZWO294 MC Pro. Since I posted, I verified once again, that other exposures were fine, it was just the 4 minute that dropped every frame.

Always appreciate your prompt assistance
Joe

P.S. So, could this be like a 'blind spot' on the 294? I'm wondering, perhaps I need to take exposure close, but below the 240 second capture, i.e., 239 s and 241 s), might this help in the diagnosis?

Hi Joe,

yes, it would probably be a good idea to experiment a bit (no need for dark sky for this) and see if

a) is there a cut off beyond which it doesn't work (ie 240s +) or is there a bad spot at 240s with 239 and 241 working?
b) does this happen with normal capture/imaging as well as in capture dark.

Sometimes it's weird the way that a few extra bits of information help the big picture suddenly make sense.

cheers,

Robin

Hi Robin,
Well, today’s experimenting has only led to more confusion. I captured darks at 239, 240, and 241 seconds. And there were no dropped frames in any of the captures! My indoor set up was exactly the same as yesterday’s when the 240 second frames were dropped. I will continue to see if this problem pops up again. For now, the only conclusion might be, poltergeist!

If I run into this again, I will post the details.

Once again, thank you for SharpCap and all that you do,
Joe

Hi Joe,

were your USB cables different when testing indoors? Longer USB cables can lead to reduced stability.

cheers,

Robin

No, everything was exactly the same. I’ll continue to see if this was just an anomaly.

Joe