Two overlapping 3000-frame AVIs were captured with AstroDMx Capture for Windows through an f/5.5 Ekinox 80mm ED refractor fitted with a Baader OD 3.7 solar filter, with an SVBONY SC432M air-cooled CMOS camera, fitted with a Baader Ca K-line filter and a 5x Balow lens alone (giving 3x increase in focal length).
The equipment used
Flat frames were captured while the scope was pointing at the Sun. using a material that I have previously used for making H-alpha solar flatfields. It is 0.1mm thick, translucent thermoplastic polyurethane, frosted waterproof material. The material was stretched over the front of the Baader solar filter material and was held in place with a rubber band. The material was a low cost purchase from Amazon and proved to be a very effective diffuser.
The setup for flat field capture
The best 95% of the frames in each AVI were stacked in Autostakkert!4 with 1.5 Drizzle. The two resulting images were stitched in Microsoft ICE. The image mosaic was wavelet processed in waveSharp and post processed in GIMP and ACDSee.
Ca K-line image of the Sun
Although the SC432M camera is intended for use with long focal length telescopes, this experiment shows that it can be used successfully with short focal length scopes and a Barlow lens. It must also be remembered that the diffuser material is NOT a solar filter and MUST be used in conjunction with the proper solar filter if the Scope is pointing at the Sun. However, it can be used without the solar filter only if the scope is pointing at a different part of the sky, well away from the Sun in order to capture flat fields.
