The basics of film development
Pronounce « lay fond.ə.mento ». It means « the basics ». This page contains indications about the basics of film development and enlargements. Not really for absolute beginners (you remember the song by David Bowie ?). So, you know how to put the film on the spool ; you heard about the Massive Dev Chart and you look up development times on the internet ; and you also know that film is normally developped at 20 degrees Celcius and inversion is done every 30 seconds during 5 seconds and at a speed that allows you to give two half turns to the development tank. You have heared about system zones and you experience different films and developers.
If you have any questions on the above, just drop me a line.
Exposure …. ? Sure !
It’s all about « getting it right », and let’s say « right » is an equilibrium and more precisely it is the intensity of light (aperture) projected on the film (sensibility) during a given period of time (speed). So « right » is that equilibrium between sensibility, intensity and time. Where, for a given sensibility, I double the intensity of light, I reduce the time by half and vice versa. Easy: out of the three parameters, the sensibility changes only when you change film roll. Actually, at the moment I take the picture, the lightmeter tells me where (theoretically) the equilibrium lies. For example as 100 ASA film exposed at f16 during 1/125th of a second means a rather low sensibility, a low intensity of light and a fairly standard periode of time (1/125th of a second). Sensibility and intensity are low because the amount of present light is high. Doubling the intensity of light ot f11 means that the duration should be reduced by half to 1/500th of a second. Some old voigtlander lenses had a button linking speed and aperture. Hasselblads still have that.
So it seems easy. Exposure is adjustment of thee variables: sensibility, aperture and speed of which « sensibiliy » is normally fixed.
Now the point is that the equilibrium can be reached quite easily at the moment of taking the picture since most camera’s have a well functioning light meter. But that equilibrium needs to be developed. And once the film is developed, the photos need to be enlarged. Development can alter the equilibrium. And printing can do that too.
The successive operations of film development and printing are actually part of the manner in which a given scene is translated into greytones on a sheet of paper.
Getting the right exposure is very nice, but it is not more than a starting point.
In practice, let’s say I take a picture of a beautiful lady sitting in front of a white wall on a bright sunny day, with loads of light falling on the lady and the wall. Look carefully and you’ll notice that the wall isn’t white : it has nuances and it probably also has a very hard shadow. When you take the picture, the equilibrium reaches the film as indicated by the light meter. So the camera got the exposure right. I’m using an Ilford HP5+ film and exposed at f5,6 during 1/125th of a second.But then you need to develop your film. This is where you exploit the exposure. For this, let’s use Ilfotec LC29 developer diluted at 1+19. The development notive tells me I need to develop for 6 minutes and 30 secondes at 20°C.
Film development is exploiting the exposure
For example : on the final print, you want the wall to be completely white (easiest example). You can make that wall white by:
- overexposing at the moment you take the picture, i.e. you increase either aperture to f4 or reduce speed to 1/60th.
- overdeveloping, i.e. rather than developing 6 minutes and 30 secondes at 20°C: increase time to 7 minutes 30 of increase temperature.
Over developed fim or underdeveloped film ?
So you have developped a film, and after washing the film you take it of the spool but surprise : the film est extremely black ! Have you developped too long or not long enough ? Have you agitated to tank too much or not enough ?
- Film too bright ? It is underdeveloped. Why ? Either you have used an expired developer, or not diluted correctly or not developped long enough, or not agitated enough. Next time better : make sure you use a good developer ; make sure your dilution is correct ; make sure your development time is correct and agitate as I indicated above.
- Film too dark ? It is overdeveloped. Why ? Wrong dilution, or you have developped too long ; or you agitated way too much. Of course when a product needs to be diluted 1+4, that mean that you use 1/5th of developper and 4/5th water (200 ml developper + 800 water make 1 liter of usable product), i.e. 1+4 means 20% developer, not 25%.