Here it is, I exposed a roll of ISO 400 film thinking it was a ISO 100. I know in order to have good negs I need to pull it by 2 stops during developing. Question is how do I go about it? I have not really done any processing in quite a while and am quite worried of messing it up. I would like to use T-Max dev for Ilford Delta films, is it advisable to do so?

-- Kenneth Seah (seahnet@singnet.com.sg), September 04, 1998

Answers

Well, at least this was the "safe" way round. Modern B&W film is highly tolerant of a couple of stops over exposure. I would probably just develop as for ISO 400, or might pull the development by 10%.

If the shots are really important, the best advice is to put the film to one side for now. Shoot another roll of ISO 400 at 100, under similar conditions (especially, with similar contrast), and try it with your chosen developer for a chosen time. If you don't like the result, try again with a different development time. When you are happy, you can develop the original roll.

If you haven't done any processing for a while, I really think a trial development is a good idea, to make sure you haven't forgotten anything critical.

If you just develop as if you had shot at ISO 400, the negatives will be a rather dense. But the shadows will be beautiful! If you pull the development, the highlights will be less dense, but the contrast will decrease. You have to choose which "fault" you want.

Film and developer manufacturers publish tables for their films and tables, and you can get more specific advice from them. As a general, very rough rule, subtract 10-20% for each stop of over-exposure. So you could could develop for between 65% (80% * 80% = 64%) and 100% of the standard time.

I haven't tried that film/dev combination. There are many people who may have done, such as http://www.chris-iris.com/.

-- Alan Gibson (gibson.al@mail.dec.com), September 04, 1998.

You did't mansion which film you have exposed. In my experience I increase/decrease 20% for every push/pull process. As an example if I expose TMAX 400 into 100 iso I will make a pull process of 20%. My TMAX 400 is 5 minutes 10 second at 26 degree C . When I expose 400 into 100 iso my developing time is 4 minutes 8 seconds in TMAX developer at 26 degree. Every film is washed at normal water at 26 degree because the temperature will be the same. Agitation will be every 30 seconds. Hope you will find you answer.

Thank you Mohammad Irfanul Islam Darkroom Section Drik Picture Library http://www1.drik.net http://www1.drik.net/darkroom

-- Mohammad Irfanul Islam (darkroom@drik.net), September 05, 1998.