More experiments: the Hoya 25A filter cuts around 590nm. Results are completely red in-camera so it is harder to compose, focus, and meter. It's even easier to blow highlights, so underexposing is usually necessary. Most other colors are gone but with a custom WB and Foveon Classic Blue color, I found it possible to get blue skies back. Combining this with a CPL should result in dark blue skies.
I started shooting infrared film because it is a different flair I am getting with film compared to my digital IR. Those were taken yesterday and home-developed and scanned. Rollei Infrared 400 film, taken with Leica M6 camera and Voigtlander 25/4 LTM lens plus Hoya R72 filter:
