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under & over exposure compensation during processing
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Firstly let me clear up, I dont use film & have never used film outside of a point and shoot disposable.
Im very curious though regarding the overlap or similarities between digital and film, as im aware that a lot of names for manipulation tools in photo editing software ( dodge, burn, crop etc) came from photo development labs.
My question is regarding exposure. We all know its preferable to get the exposure correct in camera first time. But I know that its very rare that I dont move the exposure slider in the RAW editor even a little bit one way or the other, and i sometimes even make a copy of the RAW, expose one for the sky in raw editor, the 2nd for the foreground and blend them in photoshop to get a nicely exposed image.
In film photography, how much flexibility do you have when it comes to exposure control after the image has been taken, i.e. during development/processing?
In reality how often would people use this flexibility?when you process (black and white) you have huge control over the exposure, provided you know already without seeing it which way it has gone. you can adjust time, temperature and dilution of chemistry to compensate. of course if you push or pull the film by a lot you have certain compromises – i once pushed 400iso film to 3200, i got a roll of images but they were totally posterised and very grainy. an interesting look if thats what your after.
in cases of over exposure you can compensate while printing although exposure times may end up quite long and you might need strong filtration to bring up the contrast. you can also bleach the negatives with a reducing agent, you would be surprised how much of an image can be hiding in what at first appears to be a totally black frame.
in terms of the comparison between film and digital there is one major difference. Film is forgiving of over exposure – the information is in there somewhere and can be gotten out with a variety of tricks. in cases of under exposure there is nowhere near as much one can do. digital is the opposite – once the highlights are blown out thats it but under exposures can often turn out to be quite successful.
color film is much more sensitive and there is far less latitude than with black and white. slide film even more so. slight under exposures can be very successful at making colors pop out but thats about it.
If you’re thinking black and white then your golden rule is to expose for the shadows and develop for the highlights – the shadows on a negative are the thinnest parts of the image, so you need to make sure some light hits the halides which can later be developed – you do not want these parts of your image to be completely black on your final print. And that is taken care of by the exposure.
Then you can adjust the development time (or temperature) to ensure highlights are developed correctly. If in effect you overexpose (i.e. extend exposure time in order to ensure some details are captured in the shadow) then you need to shorten your development time.
Any bw negative can be shot at higher ISO rating (i.e. underexposed and then overdeveloped) but this will generally lead to some loss of quality – bigger grain and contrast becomes more difficult to control. Sometimes this can create quite good effects … Some developers are more flexible in this regards than others. XTOL or Diafine are probably the best examples. But then some folk like the look of HP5 shot at 1600 and developed in Rodinal :-)
So there is lots of flexibility there, the difference from digital is that there’s no ctrl+Z in your lightroom (I mean darkroom :-)
For colour analogue you’re not really getting any flexibility unless you can do C41 at home.
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