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Long exposures
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This is probably a stoopid question but anyway…
Is exposure time more important with film cameras than digital?
My limited understanding is that a long exposure ‘burns’ the image into film, resulting in deeper, more saturated colours?
Does the same apply with the digital medium?My understanding is this:
Its all about the amount of light hitting the sensor. Say you have the same amount of light, ie a normal daytime shot outside. With sensitive film (high ISO), very little light was needed to get the right exposure, so fast shutter speeds (ie it isn’t open very long) or small apertures (the hole the light passes through) were the order of the day to keep the amount of light down that was getting through to your sensitive film. With less sensitive film, to let the right amount of light in you have to keep the shutter open longer or use a bigger aperture (or both!). Big apertures are small f numbers, and vice versa. The smaller the f number, the bigger the hole the light passes thru and the faster shutter speed you will need.
So long exposures (shutter open a long time) are used when there is very little light hitting the sensor, ie at night or in a dark room. This lets enough light through to the film/sensor to get your exposure.
Thats how i see it, no idea what effects that has on colour depth, sorry!
Well, strictly speaking they’re equally important. A correct exposure is a correct exposure no matter what the medium, and the shutter speed will be the same for a given aperture and equivalent ISO on either film or digital. Longer exposure times on either will eventually result in overexposure, and losing of highlights. This is particularly the case with digital, where there’s an abrupt cut off and beyond that point you have no useful data, and no way to retrieve it. Negative film will give you more leeway exposure wise, but slide film is about as unforgiving as digital.
What you’re probably thinking about is long exposures at sunrise or sunset, the “golden hour”, which tend to be deeply saturated. The saturated colours are a consequence of warm light caused by the sun being at a very low angle. The lower light levels result in slower shutter speeds being required for a correct exposure. But try shooting the same scene, with the same shutter speed at midday with the sun directly overhead, and you’ll most likely get a white rectangle.
John
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