From uscoles.com,
Photographers set their exposure using a combination of
shutter speeds and
f/stops to get the correct amount of light on the film (or sensor--this all works for digital too). The shutter speed regulates how long the film is exposed to light coming through the lens. The f/stop regulates how much light is allowed through the lens by varying the area of the hole the light comes through. For any given film speed and lighting combination there is one correct amount of light to properly expose the film. This amount of light can be achieved with many different combinations of f/stops and shutter speeds. This page goes over the f/stop and especially its initially-confusing numbering at some length.
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From photoanswers.co.uk
Depth-of-field refers to the amount of the scene that appears to be sharp in your shot. Unlike our eyesight, which compensates for limited depth-of-field by quickly scanning different areas of the scene and focusing on near and distant points, camera lenses must obey some simple physical laws. Chiefly, depth-of-field extends in front of and behind the point you’ve focused the lens on. This zone of sharpness is not distributed evenly, however: it extends twice as far behind the focus point as it does in front of it.
The amount of depth-of-field in your shot is determined by three factors – the focal length of the lens, the aperture used and the distance from the subject.
1. Focal length. The shorter the focal length of the lens the greater the depth-of-field, and the longer the focal length, the smaller it will be. In general, using wide-angle lenses you’ll find that most of the scene is in sharp focus, while telephoto lenses are better for giving shallow depth-of-field, allowing you to throw distracting background elements out of focus, beyond depth-of-field.
2. Aperture. The wider the aperture you use the less depth-of-field you’ll get. So, using a wide aperture of f/4 or f/2.8 will mean that less of the scene will be in sharp focus than if you use a small aperture, such as f/16 or f/22.
3. Distance. The closer you are to the subject the less depth-of-field you’ll have to work with. You’ll find it easier to get greater depth-of-field if you focus on subjects further away from the camera. Conversely, if you want shallow depth-of-field, move closer. This is most apparent when shooting close-ups, where you’ll get very shallow depth-of-field.
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From Photocritic blog,
History of the website
The idea of Photocritic started in the late 90s: I had a grand idea of starting a photo criticism site, based on the Norwegian foto.no photo critique site, but aimed at an international audience, and on a far greater scale. I started looking into hiring a programmer to do the work, and started learning how to code myself as well. Soon, it turned out that the idea was a bit optimistic, and eventually I stumbled over a site called PhotoSIG, which had all the functionality I wanted from a photo criticism site.
By then, however, I had bought the Photocritic.org domain, and I figured it was too good a domain to just ignore. I used it as my photography portfolio for a while. In 2002, I started out as a freelance photographer, and as it turned out, Photocritic was not used as a company name by anyone, and soon, Photocritic Ltd was born:
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