Posting here because I'm not sure where to post! What's the difference between a 8x red filter and a 25 (or 29) red filter. I own a zeiss ikon 8x red filter and I'd like to try an Infrared film, so i wanted to know if it's good, say like a 25 red filter which is recommended for IR photography. Thanks
Here's some info: http://en.wikipedia.org/wiki/Wratten_number Your Zeiss filter is probably like a Wratten #25.
I have a Hoya R25 and it is a 3-stop (x 8) filter so your Zeiss filter will be the same. The 29 is a deep red and is a x 20 filter (about 4 1/2 stops). I used to use the R25 with Kodak HIE but since that disappeared I have to use an R72 with the current IR films.