I see a few pics around with the Baader IR685nm pass filter. It's a broadband filter that just passes wavelengths longer than 685nm. I have an IR650 and IR720 that I use for landscape photos. Just wondering how they would work? 850nm filters are also available. I have one but it's 55mm and won't fit the optical path.
When combining IR to the other colour channels, is IR substituted for red, added as luminance or what? It can be hard to find out secrets from the masters sometimes.
