First posted 19 October 2009

Different photographers have different expectations from a film. They may buy a particular brand because they have seen that someone they admire has used it, or because it is a new type. Some buy films looking for good latitude, others for speed, acutance or fine grain. Others may be expecting contrasty, gritty results.

Buying a film and exposing/developing at the manufacturers recommended settings will usually produce negatives that are a compromise between all of these expectations. Producing the results you really want depends on an understanding of what happens when film is treated differently.
One of the first ways that new photographers try to get different results is by uprating. They read somewhere that a 400 ISO film can be exposed at a higher speed such as 1600, and then stewed in the dev to bring up the image.
This does indeed work, but occasionally at the expense of quality (not always a concern for some). Uprating can produce quite acceptable results with dilute/static processing (see the section at the end of this article) and I have rated Ilford HP5 at 1600 ISO and got results almost as good as when rated at 400.

But if the developer is one which is vigourous, the grain can be exaggerated and contrast can increase to a point where printing becomes difficult and burning in highlights is impossible. This is not always a bad thing, if you look at the work of Bill Brandt you see what can be done creatively with a film which is mistreated in this way.
Going the opposite way, if a film is downrated a couple of stops and the development time is reduced, a finer grain and a longer tonal range is produced. This can look absolutely stunning with larger negatives, especially when photographing subjects with a lot of subtle highlights such as sunlit clouds, or snow scenes at night.
The importance of agitation.
When I did lots of different ratings and development times in the early years of my career, I also found that agitation could alter the look of a negative.
Normal agitation is usually taken to be three inversions of a tank every minute and increasing the number of inversions/agitations will increase contrast. BUT, taken to an extreme, with continuous agitation, contrast actually drops!
I think it is because the developer is not allowed to sit on the surface and work properly when constantly in motion, -but I’m not a scientist, I’m a photographer, so I may be wide of the mark there.
Whatever the reason, there is a marked drop in contrast with continuous agitation as I have just mentioned, and when coupled with downrating produces a negative which has amazing latitude for highlights or overexposure. This means that a reading can be taken from the shadows to ensure detail, and the highlights will never be blown out.
Here is a composite image of four frames of the same film, The film was Ilford HP5 and the developer was Ilford ID11 stock solution at 20C with continuous agitation for four minutes.

These frames are; top left 100, top right 50, lower left 25 and lower right 12 ISO. As you can see, any of these frames could be printed. From this you can understand how the technique could produce a ‘flexible negative’ (to quote my late friend Barry Thornton), and therefore how well they could compress a high contrast scene.

Dilute/static development (also known as stand development, though there are many different methods of this).

Mix up a 1 – 3 solution of Ilford ID11. That is, one part of stock solution (normal strength) mixed with three parts of water.
Get the temperature to 20C
Pour into the tank and agitate ten times.
Start the clock.
Give three inversions every 30 seconds up to ten minutes.
When ten minutes have passed, put the tank down and do not move it at all for 50 minutes. Try to keep the temperature fairly constant.
When that time has elapsed, agitate the tank three times and repeat this agitation each minute.
After ten minutes pour the developer away and use a normal stop bath (Not too strong, weaker is better).
Fix as normal, wash and dry.

With this development method, Ilford HP5 can be rated at 1600 ISO and can produce very good results.

Here is a scan from a 10×8 print made on a Grade 2 paper from one such negative. On the print you can see detail in the dark corners and the sunlit highlights.