Adox/Efke Films: True to Their Box Speeds?

Hi Everyone,

I've decided to shoot about twenty rolls of Adox CHS 100 Art in 120 size. I'm looking for a replacement for Agfa APX100. I also plan to pick up some 50 ISO rolls as well. The instructions with the film state not to overexpose. A recent thread on Adox/Efke another APUG member also suggested not overexposing these films. OK but how much over exposure is too much? As a rule of thumb I rate my film at half the box speed, regardless of the brand or speed film. Living in LA this I find the best way to open up the deep shadows a bit thanks to the bright sun we have here most of the year. I use an incident meter and develop slow and medium films in Rodinal 1+100 with gentle agitation. So can I get away with box speed with Adox/Efke films and still get decent shadow detail? If so would this make these films true ISO actually a stop faster? Thanks for replies.

The Efke R100/Adox CHS 100 is very forgiving - much more so than APX100. Efke R100 has been sold rebranded as a ISO 200 film. It handled over- and underexposures quite well. The "perfect film" for box cameras. Shadow detail is very good.

The ISO 25 and 50 films are very different emulsions than the 100. Orthopanchromatic, and the contrast easily gets too high if you overexpose (but it CAN be controlled if you cut the developing time). Their box speed were ISO 20 and 40 before they started to DX code the 35mm cassettes, so I shoot them at ISO 20 and 40.

IME, they seem to be exposed well when rated at box speed, but are at least one whole grade too flat when developed at the manufacturer's recommended time. I rate at box speed and up the recommended time by 25% when using the 100.

The 25 and the 50 are pretty contrasty, so I overexpose them in high-contrast light, and reduce development time. However, I do not re-rate them as a matter of course. I simply manually over expose them. I don't really use the 50. Just the 25 and 100.

It does depend on developer and development method, but I always shoot the 25 and 100 at box speed. I usually develop them in Rodinal 1+100, occasionally in PC-TEA 1+50.

A friend who uses continuous agitation with PC-TEA rates the Efke 25 at 16.

Hmmm So I guess I'll try the 100 at 100 (or 80 but that probably won't make a big difference right?) and develop a few minutes more (right now have this at Rodinal 1+100 for 15 min at iso 50). For the 50 speed film I'll rate it at 25 and cut development. I've been doing this for years with Pan F. Thanks.

Steve Beskin is probably one of the few on APUG with a calibrated sensitometer to be able to see if ADOX is fibbing with the box ISO number. But its not any big deal. You should be exposing at your personal exposure index anyway. Search for "exposure index" or "zone I test"