setting aside all chemical reactions, which I won't understand, what happens when you develop a roll of film? Do parts of the film turn from opaque to transparent? If this is the case, will developing for too long make the transparent areas on negative, ie black bits on print, more transparent and therefore more black, increasing contrast but lessining detail in dark areas? I want to know whether I've over-developed or underdeveloped. I think the contrast of the shots I took was OK. I'm using Tri-x with T-max developer 1 part dev to 4 parts water, at 20-22c. Thanks Greg

-- Greg Brosnan (gbrosnan@infosel.net.mx), May 07, 1999

Answers

It's easier to show than describe in words (try a good book), but essentially: overdeveloping will make the dark parts on the negative even darker, and won't change the transparent parts much. So a print will look lighter, unless it is corrected (which it usually would be). Overdeveloping also increases contrast (simply because the darker parts are darker).

-- Alan Gibson (Alan.Gibson@technologist.com), May 08, 1999.

The film does not turn from opaque to transparent--what really happens is that the exposed part of the film turns opaque and the rest of the unexposed portions of the emulsion get removed by the fixer, leaving the clear areas on the developed film. Basically, development converts silver halides to pure silver, which then appear as black flecks in the film emulsion (the opaque part of the developed film). When you over-develop you convert more halides to silver, so you get blacker black areas. Also when you over-develop, sometimes the development action is so vigorous that it carries over to unexposed silver halides; this is known as contagious development and results in "fog", or black areas that should be clear.

-- Ed Buffaloe (edbuffaloe@earthlink.net), May 14, 1999.

Greg,

Basically, development will have a lesser impact upon the shadow areas of your image (those that are light or clear on the negative.) Exposure of the negative will determine how much detail, if any, will occur in the shadows. Development makes its impactin the highlights, something that exposure won't impact as much.

Giving your film proper exposure is essential -- no amount of development nor printing will be able to create deatil where there is none on the negative. You have to put some meat on the bones, and give the developer something to work with.

Giving your negative plenty of development make make for a contrasty negative, but then you will be able to print it on lower grades of paper (or lower filter settings if you are using variable contrast paper.) The advantage of using the lower setting/grades (0 and 1) will offer you the greatest range of greys, something that the higher grades cannot do. You can always print down the blacks. Just expose your paper for the highlights and adjust your contrast control for the blacks, if printing them down is not an option.

Check out Ansel Adams "The Negative" for information on how to make proper exposure and development tests. It sounds complicated, but it is easy, if only time consuming. This way you will know exactly how your film and paper will respond to certain exposure and development situations. It takes the guesswork out of it.

Good luck.

-- Mark Finhill (Finhill@keyedin.com), May 18, 1999.