Gast
Hello,
Can anyone give me a rough guide as to the best development time for an Efke 25 in a 1:2 D-76 solution using the agitation method?
The film was exposed at 50 ASA.
Unfortunately, I can only ever find information for a 1:1 mixture in the usual online sources.
I was once advised that, as a rule of thumb, the development time for a rotary process should be 1/3 shorter than for a shaking process. Is that correct?
Ciao, Micha
zensusa
Hi Micha,
That figure of one-third is incorrect! I use a Jobo rotary processor for all my films, and I can tell you that, unlike tilting (depending on how often you tilt per minute), rotation requires a reduction of only between 10 and 15 per cent. Any more than that would be a complete mistake! By the way, you can find my rotation data/times for all three Efkes elsewhere in this forum, though they refer to R09 and sheet and roll films. So if you’ve exposed the Efke 25 as 50 ASA, it’s advisable that, if you’re using a mixed-light enlarger, you extend (multiply) the ‘normal’ development time by a factor of 1.4. With a condenser, it should be correspondingly shorter, by a factor of about 1.2. Incidentally, if necessary – provided the exposure is correctly metered – the Efke 25 works fine without extension; most users would probably not even notice, as the negative would still produce acceptable results even without extension.
Have a lovely evening and best regards
Gast
Hi zensusa,
Thanks very much for your explanation, but I’ve got a couple more questions:
- By ‘standard development time’, do you mean the time for the stock solution?
- Does your multiplication factor refer to rotation and the 1:2 dilution at 50 ASA, or just one of the two?
Bye, Micha
zensusa
Hello Micha,
As my development times are based on Calbe’s R09 developer (and certainly not on D76), there is no ‘standard’ in that sense, because you should not develop with the undiluted developer concentrate! So there is no 1:2 ratio or dilution either! The standard dilution is 1:40, as I have stated. However, R09 allows dilution ratios ranging from 1:20 to 1:400 (e.g. for stand development). The usual, common dilutions are 1:40 and 1:80. These should generally suffice for normal situations.
**** My times therefore refer to a ratio of 1:40 (1 part developer concentrate to 40 parts water)****
The term ‘standard development time’ means that, using the specified development time, you obtain a negative that can be printed on paper with a gradient of between 2 and 3 (roughly speaking, i.e. standard paper) when subjected to an enlargement! All time specifications – regardless of which film manufacturer or chemical supplier provides them – refer to this. In this context, the film manufacturer also specifies – or is required to specify – the gamma value achieved at this “normal” development time; in other words, with an enlarger/lighting system that implements or requires these gamma values, one can then achieve the desired paper gradations in the range of 2 to 3! However, the film manufacturer also assumes that the subject contrast when taking the photograph is within the normal range (around a 5-stop difference between light and dark) and, of course, that the film is exposed correctly! If either of these conditions is not met, even the normal, i.e. ‘correct’, development time will not produce ‘normal’ negatives resulting in a gradient between 2 and 3. In short, a dull, grey November landscape with ‘normal’ exposure will not produce negatives that can be developed with the ‘normal’ development time, as they would be too flat and could certainly only be developed on paper with a gradient of 5 (if at all). So the shooting conditions also determine which development time is the right one for the shot taken.
It’s all a bit complex and lengthy to explain here, as so many factors come into play.
So, my suggested times produce a negative that can be exposed well on Classic paper with a gradient of 2 or 3. Provided you have a mixed-light enlarger (i.e. soft light! – such as Dunco, Kaiser, Jobo/(lpl enlarger etc.)).
I’m assuming you have such an enlarger with soft light, i.e. a mixing box; in that case, you should multiply the standard development time for the Efke 25 by a factor of 1.4 (with hard enlarger light, multiply by only 1.2). This would bring the development time into line with a 50 ASA exposure, because essentially you have underexposed the Efke 25 by one stop; to compensate for this underexposure, you therefore multiply the time by the factor 1.4 (or 1.2 as just described).
So, this factor has nothing to do with the dilution of the developer but falls within the realm of film exposure, in this case ‘pushing’.
Well, I hope the explanations have helped.
Have fun, and one more thing: all tips and advice are no substitute for the experience of your own failures. It sounds a bit pompous, but it’s true.
Best regards
Zensusa / Lo van de Renne
