SharpCap Forums

Hi,

the individual flat frames do get saved temporarily (to your temp folder) and then deleted again once the master flat has been created. Right now, you cannot specify to keep them, but it is something that I am considering. To answer your other questions...

1) a)You have a mono camera, so the 'mono' choice is not relevant - the flat will be mono anyway. That choice only applies to colour cameras
b) I am guessing that you had a dark frame already selected when capturing the flat (perhaps inadvertantly). If that is the case then SharpCap assumes that you have already taken care of dark subtraction by selecting a dark flat and does not offer the bias/subtract dark options

2) SharpCap captures a few extra frames when taking both bias and dark flat frames. It discards the first few frames captured, since on some cameras (or depending on how quickly you press OK after covering the telescope), some of these frames may still be taken using the previous camera settings or with illumination. Better to take a few extra frames than to use ones that might be incorrect

Why this is happening when subtract bias is selected and unchangeable is a good question though - I will investigate.

cheers,

Robin

Hi Robin
I’m unclear in ‘1b’about having a ‘dark frame already selected’. I hadn’t been doing anything with dark frames and was only just then beginning work on some new flats for the 294 mm.

As soon as I was done previewing exposures and confirming the adu values, I opened the ‘Capture Flat’ tool and noticed again that all I could select was how many frames and whether I wanted the flat applied once it was done. Everything else was greyed out. The choices selected in the greyed out boxes were: mono and bias subtraction (not dark flats) which were fine with me anyway but it does bug me that I could not have changed them if I had wanted to.

So, what is going on with all the files labeled Flat Darks that were in the Temp Folder? Subtract Bias is what had been selected and greyed-out so why is there anything labeled dark flats? Are these files just incorrectly labeled ‘Bias’ frames? If not, and they are dark flats, were my flats corrected with Dark flats even though the menu showed ‘subtract bias’ as the selected calibration for the raw flats?
Gary

Hi Gary,

ok, I think I just found another way that the options to subtract dark, bias, etc can be disabled - if your camera is in still mode, they become enabled after the first frame is captured following the showing of the 'capture flat' window. Maybe that is what happened to you. I will fix this, but the workaround for now is to use the 'framing shot' button to capture (and not save) a single frame after opening the 'capture flat' window.

As for naming the frames in the temp folder, I have a feeling that it might be a follow on bug from the above issue - let's get this first one fixed and see if that resolves everything.

cheers,

Robin

Thank you Robin…..amazing that sw seems to have a bit of a mind of its own sometimes..
best to you for 2022.
Gary

Hi Gary,

software is usually OK unless you start changing it In this case the original code set those controls enabled when the first frame arrived after opening the window. When 'live view' was the only option in SharpCap that worked fine. Along comes still mode and while I updated the code to actually capture the flat frames to cope with the change, I failed to spot that the enabling of the buttons was depending on live mode

cheers,

Robin

Ummm…I’m re-reading the last several posts and am recalling that I believe I was using the framing shots ( like that feature a lot) to test the histogram location at various combinations of flat panel illumination and exposure. I can’t say I’m 100% sure of that so I’ll test this later this morning (Boston).
Thank you,
Gary