 Mary E. Hamel |
Purposely Over or Under Exposing I am confused about the concepts of why one would over or under expose a shot using the EV buttons. You under expose to increase saturation, but any particular time of day or light that is best suited for this? What about the opposite? I saw a blurb under one of Bryan Peterson's gallery shots of a pool in mid-day sun; he overexposed... doesn't that mean slower shutter speed? That doesn't seem right to me, so I know I'm confused! What does (for instance) EV+1 really mean, overexpose by one stop? Also, is this similar to pushing/pulling film? Please help, this really bugs me!
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Jon Close |
EV+1 means one stop additional exposure value, not necessarily "overexpose." There are several aspects to this. (2) Slide films tend to exhibit more saturated colors when slightly underexposed, usually -1/3 to -1/2 stop. Color print film is the opposite. Slight overexposure gives it more saturation. You can make this adjustment either frame by frame with the exposure compensation, or for the whole roll by adjusting the ISO setting. Some slide films, such as Fuji Velvia 50 is already formulated for saturated colors, so some photographers rate it at 40 (+1/3 stop) to get a little less color saturation. For (1) and (2) the film is developed normally. (3) There are situations where the speed of the film does not allow you to use the shutter speeds and aperture combinations you want. Say you have ISO 400 film and want to shoot indoor sports with a shutter speed of 1/250 or higher, but it's dim and the best your meter gives you is 1/125. If you change the ISO setting to 800, the meter will give you the desired 1/250 shutter speed, but the film will be uniformly underexposed by 1 stop. You then take this film to a lab that does custom developing and have them "push" it 1 stop, meaning they leave it in the developer chemicals longer to bring out the images. There is usually a trade-off with loss of contrast and higher grain in push processed film, and some films have better ability to be pushed than others. Pull processing is the opposite, rating the film at a lower ISO (so you can use longer shutter speeds or smaller apertures) and shortening the developer time. Push/Pull processing can only be applied to a whole roll of film, you cannot select individual frames to push/pull.
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Mary E. Hamel |
That really makes sense now. I wasn't looking at EV from a camera's exposure metering calibration as to light vs dark subjects. All of the info you gave is very helpful -- thank you for taking the time to answer.
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