EFKE ISO 25 film- spectral sensitivity change?greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I just received a bunch of EFKE KB 25 and R25 film and I notice it is marked "panchromatically sensitized..."- the old KB 14 (ASA 20) was marked as "orthopanchromatic". Does anyone out there know if FOTOKEMIKA has tinkered with the spectral sensitivity of this film? I SURE HOPE NOT!!! I haven't shot any of it yet to compare but am curious if someone out there knows firsthand. The exposure charts still indicate one stop more exposure for artificial light so maybe they have not tinkered with it in that regard. The EFKE (aka ADOX emulsions in earlier days) films are uniquely beautiful as orthopanchromatic- some things are better left alone. Thanx in advance! 8-)
-- Alex O. (firstname.lastname@example.org), January 11, 1999
The German distributor (Fotoimpex Berlin) said Fotokemika would use the original Adox emulsion recipe or all three films (KB25, KB50, KB100). The spectral sensitivity curves on the data sheet showed that KB25 and KB50 are not as sensitive for red light as KB100 and other standard panchromatic b&w films. I checked it by taking a deep red filter (no 29) and there war indeed a nearly blank negative (the filter factor for no 29 would be about 100 to 200). So I would consider KB25 and KB50 (resp. R25 and R50) as orthopanchromatic and think they behave as the former KB14, KB17, and KB21 films. I
-- Thies Meincke (email@example.com), January 22, 1999.
Alex, the Swedish distributor for EFKE, Photax, says that KB (Klein Bild) 25 & 50 and R (Roll film) 25 & 50 are orthopanchromatic but the KB100 and R100 are panchromatic. They go even further and claim (with some reservation for my translation: "The film (25 & 50) is ortho panchromatic which means that it "draws" red on the correct place on the grey-scale." (source: www.photax.se)
There used to be a R40 (I still have 5 rolls) that was the first film I tried out with the zone system. It was very fine-grained with Paterson Acutol. And the grey-scale was quite beatiful for nature-photography, I haven't tried it for portraits.
Alex, I'd be interested to know what YOU like about the EFKE films and what developers you use.
-- Peter Olsson (Peter.Olsson@sb.luth.se), January 25, 1999.
The spectral sensitivity of these films has not changed. The 25 and 50 speed films still have reduced sensitivity to red, but are nonetheless panchromatic.
-- David Foy (firstname.lastname@example.org), January 15, 2003.