aXL
Hi there!
I’ve repeatedly come across comments on this forum suggesting that a certain amount of Rodinal (concentrate) should be in the tank per film.
However, with my standard dilution of 1+100, I’m well below all the recommendations I’ve seen, be it 15 ml per film, 10 ml or whatever else around that figure.
Strangely enough, I’ve never had any problems with my batches. The last batch was 8 films (of the less important sort) all at once in just under 2.4 litres of Rodinal 1+100. With 24 ml of concentrate used, that works out at just 3 ml per film! (The film type: Maco UP 100+ KB, exposed as 50 ASA; exposure time 18 minutes, agitation: once every 3 minutes)
Before I try running a single film in a litre of solution (to get at least 10 ml), I’d really like to know what the problem is if I’ve barely any concentrate left per film in the bath. Does that really make a difference to the quality?
Thanks in advance,
Axel
rherz
Hi Axel,
It’s actually quite simple: if you go below the minimum volume, it could happen that your film has used up all the developer and isn’t fully developed yet – in which case the development process stops, no matter how long you leave the film in the chemical bath.
Normally, however, manufacturers have to include a decent safety margin to make the process ‘foolproof’, meaning the minimum quantities are certainly set generously. Another factor is likely to be oxidation resistance, which decreases significantly with higher dilutions. Your developer might go off before it even reaches the can and the films.
I hope that helps a little.
Best regards
Robert
Gast
Hello!
The amount of developer used also depends on the type of film (more or less silver content) and the nature of the exposure/subject (lots of harsh contrasts with many dense highlights), because, depending on these factors, more or less developer is needed to reduce the exposed silver in the image.
That’s why the manufacturer naturally builds in a certain margin of safety when specifying minimum quantities (officially 10ml for Rodinal); risk-takers can of course go slightly below that, but I consider 3ml per film to be very much at the limit.
Too little developer is likely to result in thin and washed-out negatives (though possibly with greater acutance due to the developer being exhausted).
Roman
aXL
Hello there,
I reckon Robert is closer to the mark. The films I process are of the high-silver variety (at least that’s what Uncle Schröer from Maco claims, and I have no reason not to believe him). The UP 25+ in particular, which I usually develop in Rodinal, is by no means low in silver content at 9 mg per m².
Of the 8 films mentioned, 2 had been exposed to far too much light. The result was significantly over-developed, extremely dense negatives. So even at this high dilution, Rodinal is anything but weak.
I’m becoming increasingly convinced that this ancient formula is still underestimated, isn’t it?
See you later,
Axel
fotohuisrovo
Hello Axel,
I’d like to refer back to a quote from Mr Wolfgang Holz of Agfa:
Author: wolfgang holz (213.168.99.---)
Date: 29/10/03 10:39
Since I’ve already been quoted, I’d like to say a few more words on this – as has already been noted – frequently asked question.
When a film is developed, it requires a certain amount of developer. This developer is then used up during processing. Agfa now recommends a minimum quantity of 10 ml of concentrate per roll of film. Depending on the dilution, this can amount to more than 500 ml. The fact that it is 10 ml and not 7, 8 or 9 ml is because the manufacturer cannot know in every single case how the film was exposed, that is, how high the proportion of black is in the negative. This is because, when photographing at night, depending on the subject, very little silver salt is exposed and consequently very little is developed, which in turn means that little developer is used.
Agfa has therefore assumed an average exposure value, and the 10 ml is based on this average. This means that it is certainly possible to manage with less, e.g. 5 ml per film. Using 10 ml per film ensures, in any case, that the results are good and reproducible. Anyone wishing to use less concentrate can, of course, do so, but it is advisable to test the results beforehand. And not just ‘normal’ negatives, but also non-standard ones, as otherwise the negatives may turn out too pale.
Kind regards
Wolfgang Holz
Agfa-Gevaert AG
I think it’s clear what this explains.
Best regards from Holland, :rolleyes:
Fotohuis RoVo
www.FotohuisRoVo.nl
Robert Vonk
