Adox chs 25 in Rodinal?

unibonded said:

I did my first test film yesterday, 13 mins in Rodinal 1+100 with minimal agitation for 13 mins (as Lee suggested). Results were very thin – I shall try again tomorrow...

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Sorry if the way I combined posts wasn't clear. I was suggesting 10-12 minutes with "normal" agitation. For minimal agitation / semistand, I'd extend times by about 50% from there.

Lee

No problem Lee, I'll give my next films a go at more like 18 mins and also try some regular agitation, see how that goes.

My German is very rusty - but....

Philippe Grunchec said:

Tom, the Fotoimpex catalogue says: "Die Gelatine der CHS Filme kann nicht si gehärtet werden wie es bei einem modernen Film der Fall ist. Der Anwender sollte daher die nasse Emulsion mit Vorsicht behandeln".

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Philippe: Here is my German/English translation attempt:

"The gelatin of the CHS films is not hardened like modern films are. The user should handle the wet emulsion with caution."

Very good translation, Tom! My English is also very rusty, I'm afraid...

unibonded said:

I've had a look around, but can't find much of an answer to this one...

I've been using some Adox CHS 25 in both 120 and 4x5, just wondering what a good starting time is for developing, I'll be using Rodinal, hear it's best at 1+100 or 1+50

Thanks

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Rodinal 1:50 10min for 20gradC. Will blow your mind.

unibonded said:

I've had a look around, but can't find much of an answer to this one...

I've been using some Adox CHS 25 in both 120 and 4x5, just wondering what a good starting time is for developing, I'll be using Rodinal, hear it's best at 1+100 or 1+50

Thanks

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Rodinal + Adox (Efke) 25 are a magical combination. No need to worry about grain being excessive.

1:50 for 10min at 20c with give you amazing results.

Wishy said:

I've only ever used R09 to be honest, it was cheaper

I've always used 1:40 in place of 1:50 and the same times, never had any cause for complaint, but without comparing the two side by side having exposed and agregated the same (In the same temperature water), its hard to tell. Everybodys processes are different.

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R09 IS Rodinal (merely an older formulation).

What processing time is recommended for Adox CHS 25 exposed at EI 50, using Rodinal? (The box the film comes in recommends Adox APH 09 1+40 for 8-9 mins -- presumably at 20 deg C, though it does not appear to say so.)

Thanks BTW for the very useful comments on this thread.

Rgds, John

sharpless said:

What processing time is recommended for Adox CHS 25 exposed at EI 50, using Rodinal?...

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That is in popular terms called "pushing" and in more practical terms "expansion" (of low subject contrast).
Pushing as such implies sacrifising the shadows and rising contrast in the mid and high values. This because it's very difficult to simply rise the sensitivity of the film beyond what it's designed for.
Expansion may give you 1/3 of a stop of better sensitivity. Again the contrast is rissen.
Pushing and Expansion are really the same thing, where "Expansion" is a better description of what is really happening when developing more than normal.

But Adox/Efke 25 is not a good film for that. The true basic film speed is around EI 12-20 (depending on choice of developer). Nor is any other slow film as they all tend to give you quite a lot of contrast to begin with. A general observation is: "The faster the film, the lower the contrast". If you need a faster film, there are plenty of films around, including Adox films (e.g. CHS 100 which I rate at EI 50).
This film has a "look" of its own, which is why I like it. There is no other film like it and the lack of film speed is one of its assets. (I use it in 4x5" with barrel lenses used wide open. This gives me a long exposure time and the film charateristics in itself gives an oldfashioned look and feel, much different from modern films.)

A shorter answer, if you don't like the discussion above , is 14-16 minutes. (But you will get very contrasty negs... Why? See my discussion above. )

//Björn

Björn -- thanks for this advice.

On the box of Adox CHS25 it says: If exposed to ASA 50 for increased speed and optimum differentiation of highlights the following developing times apply....

They go on to warn against overexposure. The same message appears on the Adox web site www.adox.de
They say: This means for example the film is generous against under exposure or reciprocity effect but can´t cope with over exposure because it can´t shield itself from too much light

I am surprised that they do this if the film should actually be rated at 25 or slower! Is it because of the type of developer?

Thanks again for your advice.

John

While I really like Fotoimpex (which is the company behind the Adox brand name nowadays, if I have understood matters correctly), they do what everyone else do. I.e. a bit of exaggeration here and there. In my opinion there is no way you can get a true EI 50 from that film.
Also they are trying to imply that the film have more tolerance than it really has (... it can be exposed at ISO 50) to taking it back in the next paragraph by telling you not to overexpose. The truth is that this film is just as fuzzy about how you handle it as you would expect a slow b/w film to be. This holds true regardless of brand. Ilford PanF is just about as fuzzy. The same was true for Agfa APX25 (rip). In order to get the best out of the film you have to be as careful with it as you should be with slide film. But the same basic rule apply as for every negative film. Expose for the shadows and develop for the highlights. (For slide film and digital it reads: Expose for the highlights and hope for the best. )
The sensitivity of the film, i.e. the ISO rating comes from how much light is needed to give a 1/3 stop exposure above unexposed film. (In practical terms, a just noticable shade above pure black in a print.) This is the only way to determine film speed. A 50% increase of development is often considered to be a 1½-2 stop push, but the ISO barely changes at all. The midvalues does change by these 1½-2 steps though. The highlights are blown out of printable range and the grain of the film becomes massive too.
If I want a film around that sensitivity, I'd choose either CHS 100, TMX, FP4, Delta 100, Fuji Acros Plus-X ... which are all excellent films. (The one with most personality is probably Adox CHS 100. FP4 is well known and also sold by Fotoimpex as Adox CHM 125. There's lots of opinions and data about all of these films.)

//Björn

OK -- well, I tried it, and it seems to work fine. The film was exposed at EI 50, and I developed it in Rodinal 1+50 at 19.5 deg C for 9.5 minutes (the 0.5 was to allow for the temperature being slightly low). The negatives are quite contrasty, but not too much. They scanned easily enough. Some of the pictures were taken in bright sun of fairly high contrast scenes, and no problems there. The grain (or lack of it) also seems fine.