Hopefully the last 2.7 Beta build – 2.0.2095 now available

Probably the most significant new feature in this build is the ability to perform dark subtraction when using all Astro cameras (QHY, ZWO, Altair, iNova, ASCOM, Basler, etc). This functionality can be found in the ‘preprocessing’ section of the camera controls – you just need to select a dark frame which matches the resolution and colour space that you are using to capture. Dark frames can be in PNG or FITS format (8 or 16 bpp). SharpCap will perform basic fixes when loading a dark frame – for instance a 24 bit (8 bit depth RGB) dark will be converted to a 32 bit (8 bit depth ARGB) dark (or vice-versa) if required.

General purpose dark subtraction is not yet available for cameras being used via webcam (DirectShow) drivers. Supporting this would require significant changes to the way webcams are handled and I’m not convinced it could be done without introducing other issues. Dark subtraction *can* be used with webcams if you are using the live stacking functionality however. One thing to be aware of is that you shouldn’t use two lots of dark subtraction (in the camera controls and in live stacking – there’s currently nothing to stop you from doing this, but the result’s probably won’t be pretty!).

Final words on dark subtraction – it affects both the preview of the frame as seen on the screen and the frame as saved to any output file when capturing.

Other significant features in this build:

  • In live stacking there is now a graph of the FWHM of recent frames (on the filter tab) – this can help you set a sensible value for filtering out poor quality frames
  • The main focus score graphs for FWHM and Contrast detection now have an extra line which shows the focuser position if you have an ASCOM focuser selected – this should help you easily spot the value that gave the best focus measurements.

Bugs fixed include

  • Fix UI lock up during single frame capture which made it hard to cancel single frame sequences
  • snapshot could save to PNG when preference was for FITS
  • stop capture profile being loaded during capture

Note: The original build 2089 had a bug which sadly disabled live stacking (2 lines of code in the wrong order). 2095 corrects this as well as fixing a few other small issues.