Tip for Technical Pan users...greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
If you want the sharpness and extremely fine grain of the Technical Pan film, but don't like the way it makes red lighter and blue so dark, get a B+W 489 blue green filter! With this filter you will get a more normal grey scale!
-- Patric (email@example.com), March 27, 2001
Very interesting--what is the filter factor?
-- Ed Buffaloe (firstname.lastname@example.org), March 27, 2001.
Ed, I think it's around 2 with Technical Pan, but around 1,5 with ordinary films.
-- Patric (email@example.com), March 27, 2001.
I looked the filter up and found the following: This filter is frequently described as a heat absorbing filter because it lets the visible spectral range pass while the infrared rays from 780nm are strongly blocked. It is often used to protect IR-sensitive CCD sensors or in illumination systems.
Obviously, it must also block some visible red spectrum. It would make sense that its factor would be higher for Tech Pan, since Tech Pan is more red-sensitive. This would cut the effective speed of Tech Pan down to EI 6 or 12. Still, it would be worth trying. I keep looking for some way to make this film work for me.
Using a red filter: There is a lovely photograph in the latest issue of View Camera (March/April 2001) by Don Kirby (page 15) of a field of mown bluegrass that was taken with Tech Pan in 6x9 format. It is a remarkable image. He used a deep red filter and developed in Rodinal (1:200) for 19 minutes with periodic agitation. He says this is an N+2 development.
When I tried a red filter with Tech Pan and developed in Technidol liquid, the negatives were so contrasty as to be unprintable.
-- Ed Buffaloe (firstname.lastname@example.org), March 28, 2001.
The 489 filter starts to darken colors in the spectra from ca 570 nm. At 650 nm the transmission is 70%, at 700 nm it's down to 50%, and at 750 nm it's only 25%. Looks good! This filter is a real schott glass, so it's better than the color correction filters from B+W that are gel filters laminated between glass.
-- Patric (email@example.com), March 29, 2001.