 BetterPhoto Member |
Stepping Up or Down I've recently purchased a DSLR. Up to that I was a point and shoot type of guy. I hear see the following terms "stepping up or down", "hand held" "or f-stops". What does all this mean and what are the pros and cons of each? Thanks!
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Jon Close |
No pro or con, just different. Starting with the simplest, "hand held" is the alternative to mounting the camera on a tripod/monopod. Hand held is most convenient, but the images may blur since the camera isn't held rock solid the entire time the shutter is open. The slower the shutter speed, the more blur is likely from shooting hand held. "F-stops" refers to the aperture setting on the lens. The lens aperture is a diaphram that regulates the amount of light let in. To simplify exposure calculation, the aperture settings are standardized as a ratio of lens focal lenght divided by aperture diameter. "f/4" means the aperture diameter is equal to the focal length divided by 4. "f/8" is an aperture diameter equal to the focal length divided by 8. A particular aperture setting lets in (virtually) the same amount of light, regardless of the lens focal length. So that a 24mm lens set to f/4 passes the same amount of light to the film/sensor as a 100mm lens at f/4, or a 200mm lens at f/4. Because it is a ratio, larger f-numbers refer to smaller apertures. "Stepping up or down" is actually "Stopping up or down." It refers to changing the lens aperture. "Stopping down" means to close the aperture down to a smaller diameter (larger f-number). This results in greater sharpness because most lenses are sharpest with the aperture closed down 1 or 2 stops from wide open, and greater depth of field (the range of distances that will be in apparent focus). The trade-off is smaller apertures require longer shutter speeds.
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Jon Close |
Oops, forgot a definition. A "stop" is shorthand for the aperture setting, but is also used to refer to changes in exposure. Each "stop" is 1/2 (or 2x) the amount of exposure. Changing the shutter speed from 1/125 to 1/250 gives 1/2 as much exposure, and is a 1 stop change. One stop changes in lens aperture are do not double/halve the f-number, but instead change by the square root of 2, usually rounded to x1.4. Changing the aperture from f/4 to f/5.6 is a 1 stop change. F/4 lets in 2x the amount of light as f/5.6. F/4 to f/8 is a 2 stop change. F/4 lets in 4x the amount of light as f/8.
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BetterPhoto Member |
If you want to really dig into the terminology and the hows and whys of photography, you might check out some books. Ansel Adams published a series of three books. 'The Camera' goes over camera bodies, lens, flashes and other accessories. 'The Negative' covers exposure of the negative, including definitions and applications of the terms you mentioned. 'The Print' covers making prints. Now you won't much if any mention of digital in these books but they are an invaluable reference if you want to know what is possible. It sounds like you want to expand your knowledge and aside from ractice, practice and more practice, this is the way to go. Chris Walrath
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