SharpCap Forums

Dear Robin,

First of all, a word to tell you how much I like SharpCap. It is really a very efficient and versatile software. So, thank you.

I'm writing to you because my QHY294M camera died and with no possibility of repair, I switched to the QHY268M. This change happened at the same time as I was learning spectroscopy and occultation. I recently started to make images of good enough quality to take the time to prepare Darks and Flats. However, I have encountered two problems. I am working on a Windows 11 machine with a 2TB SanDisk Externe SSD.

First, when I use "Start Capture" for a 300 second single frame, the capture starts... But doesn't stop by itself. I have to change a setting in the control panel (e.g. USB speed) to get the image to display. Otherwise, the time countdown continues but the recording and the image display does not happen and the camera stays in Still mode. If I ask for several images, the problem is the same, but I can't get back in control. I have to reboot the machine (which is annoying when I spent 20 minutes to find my target). Surprisingly, the problem does not occur when I use the Sequencer. And obviously, it doesn't appear when I use my other cameras (ZWO178MM and QHY5III178C). This suggests that it is a driver problem.

My second problem is that when I capture an image (Dark, Flat, Bias, Light) from "Start Capture", my files are 51'644K (6280x4210), but when I launch my Darks from the Sequencer, the files are 50'997K (6252x4176). Of course, when I want to do the pre-processing, the software tells me that the files are not the same size. I saw that you answered this question in the viewtopic.php?t=4531 thread but the solution is still very unsatisfactory. Is there not another option?

Thanks in advance for your help
Sincerely
Christian V.

Hi,

I think the different resolutions you are noticing gives the key to the problem...

For some reason QHY make a slightly higher resolution available on some cameras when used in video mode than when used in still mode. I have been unable to find a satisfactory way to work around this issue to make it invisible to the user. If I try to use the higher resolution in still mode then the image has rubbish data around the edges which causes issues with stacking applications. If I try using the lower resolution in live mode then it quickly becomes apparent that the captured area is not just slightly smaller but is also offset slightly (by a possibly model dependent amount) - without getting the offset right, darks and flats would not work correctly.

Anyway, that explains the reason for the slight change in resolution, and also highlights that you seem to be capturing some of your images using 'start capture' in video mode, which is also the likely cause of the problems capturing long frames.

You have two ways to work around this...

1) Switch SharpCap out of 'live view' mode using the top-left button on the toolbar - this will force the camera to use still mode for all captures. In this mode, the camera only captures images on request, rather than continuously as is usualy with SharpCap

2) Switch the 'force still mode' control of the camer to On. This puts your QHY camera into still mode (with the slightly reduced resolution and hopefully avoiding the time out issues) while allowing SharpCap to keep 'live view' switched on.

Both of these approaches should cure your issues.

cheers,

Robin

Thank you for your answer. Have a nice day.
Best regards
Christian