Gast
Hello!
I read somewhere here that Fomapan 400 doesn’t actually have a speed of 400 and is better used as a 320 film.
I’ve just given that a go. My question is, does that mean the development time (as specified by FOTOIMPEX) changes?
(I’m using Tmax RS as my developer.) So should I stick to 8 minutes, or not?
Anyone know...
Gast
Hello,
So, if the 8 minutes were calculated for 400 ISO, you’ll need to reduce the time slightly for 320 ISO (approx. 0.8 minutes = 50 seconds).
However, this is all still within the ‘processing tolerance’.
You should definitely decide on one approach. In other words, either process all Foma 400 films at 320 from now on, or don’t, and adjust the process until it’s optimal.
Whether the Tmax RS is the optimal developer for the Foma 400 is another matter... :D
Best regards,
Mirko
dpc
Thanks for the quick reply.
What exactly do you mean by ‘tested at 400’? I thought those were FOTOIMPEX test results… Have you taken the manufacturer’s specifications from there?
In any case, I’ll develop it for 7 minutes and 10 seconds and see if I’m happy with the Kodak mix… – I can share my thoughts later.
Gast
Hello!
In principle, no 400 film actually has a speed of 400 ISO – the actual speed always depends on the developer used and on individual factors such as the accuracy of your light meter and your camera shutter; besides, manufacturers tend to exaggerate a bit for marketing reasons anyway...
For precise results, you should therefore determine the actual speed and development time for your specific combination of light meter, camera, film and developer; this can be done in a strictly scientific manner using the Zone System, a densitometer and a lot of maths, or more simply using the method described, for example, at www.barrythornton.com under ‘Unzone’.
If you don’t want to test this, it is common practice among most black-and-white photographers to expose film at 1/3 or 2/3 stops below the nominal sensitivity (i.e. a 400 film at 320 or 250) and to shorten the development time slightly (10–15%) – this gives better shadow detail, better contrast, but possibly poorer sharpness.
Regarding Fomapan 400: with that, I’d go even lower (to around 160 to 200); Foma seems to have been a bit more generous with the sensitivity rating than other manufacturers ;-) (at least that’s my experience with my equipment and Rodinal 1+50 or ID11 1+1).
Gast
Roman,
160 with R09? Something’s not right there. What dilution are you using – 1+200?
T-Max: I don’t know who fiddled with the times back then. I didn’t feel like checking now either. If there’s only one time listed in the table, then that’s the time for Foma 400 at ISO 400.
General: Did you understand what Roman explained? Depending on how long you develop, you’ll (almost) always get a normal gradient at nominal speed (i.e. Foma 400 film ‘at’ 400) with most developers.
The only question is whether Zone 1 is still there (i.e. whether the deep shadows are already washed out or still defined).
There are now developers that make particularly good use of the film’s speed, and others that, for example, produce a very fine grain (e.g. Perceptol) but halve the speed.
Depending on how tightly the manufacturer has ‘rated’ their film, it may well drop to N-2 in such a developer.
With a developer such as F09 (no higher than 1+80) or A49 (no higher than 1+1), you should be able to use the Foma 400 at ISO 400 without any issues and achieve good results. For optimal shadow detail, the +1/3 to +2/3 stop variant is recommended, with a corresponding reduction in development time of (as a rule of thumb) 10% per third of a stop.
Regards
Mirko
dpc
If I were to say I fully understood Roman (and Mirko), I’d be lying. ...but I have a vague inkling.
Is there any literature on the subject available at FOTOIMPEX, by any chance? (Do you only stock the literature listed in the catalogue?)
But for the record:
I performed an exposure on a Foma 400 at ISO 320 for 7 minutes 10 seconds, and also developed a Foma 100 and a Foma 200 in Kodak RS using the times specified by FOTOIMPEX.
The 400 is quite sharp, the tonal range is wide, but the grain is too coarse for very fine details given the speed; the shadows have definition, but other (deeper) image flaws are reproduced almost exclusively as the clear base material. (Mirko, I suppose that’s what you meant by ‘Zone 1 washed out’. It may well be that I didn’t measure the exposure very cleverly; moreover, the weather during the shoot was better than expected, so the 400 wasn’t the right choice anyway.)
The 100 and the 200 are, as expected, more nuanced and have finer grain; the rendering of shadows and details is better (I probably measured the exposure better too).
My experience with development has so far been limited to using K RS as a developer, with Tmax 100 and 400, Orwopan 400 and Efke 50 as films. Against this background, I like the Fomas.
