I'm really liking using the 100mm frac with 0.5x reducer to give me ~500mm fl for getting CaK disks. The increase in aperture from my 70mm scope to this at these short wavelengths is really noticeable. This is a 6 pane mosaic taken with the homebrew CaK filter, Lunt wedge with no ND filters as an ERF and DMK31 camera.