According to the catalogue, Adox CHS (aka Efke) films have very conservative ratings, meaning they tend to perform at higher speeds than their rated values when compared to ‘modern’ emulations.
That’s not entirely correct. Most films these days are overrated.
ADOXCHS, on the other hand, is not as overrated as other films.
That doesn’t mean, however, that it necessarily has to exceed its nominal sensitivity in all developers.
We haven’t measured whether Tanol achieves the same sensitivity performance as the ADX. The values in the ADX table are extremely honest. To my knowledge, no other manufacturer publishes such honest values in their tables.
So if you’ve read the Tanol value from a table, I’d simply factor in a reduction of up to one stop.
Incidentally, the variations within the standard for determining sensitivity allow for this, and everyone makes use of it.
The main reason we mention this with regard to CHS films is (as stated in the context) that these thin-layer single-layer films do not cope particularly well with overexposure. That is the domain of multi-layer films: resistance to overexposure.
So anyone who owns a Japanese consumer camera (which, due to its design, often gives an extra stop because the colour images then turn out ‘better’) and, out of old habit, immediately sets it to plus one for the first film and develops it to the nominal sensitivity according to the table, will almost certainly end up with a useless CHS.
If you use the ADX, you can actually adopt the specified values without testing them.
The developer’s main focus is not on maximising sensitivity.
The main focus of the ADX is not to have a single main focus, but to offer the best possible combination of all parameters without specifically increasing one parameter at the expense of another.
You’ll have to decide for yourself what’s best for you. Tanol is certainly not a bad choice. It’s top-class too!
Best regards,
Mirko
