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Category: Hobbies & Recreation : Photography
This section is more for those who may later (after becoming intimately familar with their existing gear) want to expand their picture-taking horizons.
If your camera provides for it, one day you may want to add another lens or two to your outfit, such as a telephoto lens for photographing distant objects, or a wide angle lens for covering a wide landscape.
Some people will always be content with the 'standard' lens which is supplied or fixed on their camera. The standard lens is good for a lot of normal subjects like portraits and the like; it yields an image roughly corresponding to the normal field of vision of the human eye.
Focal length of the lens, which is often inscribed on the front or side of a lens in millimetres or inches (eg, f = 50 mm), is the distance to the film from a point inside the lens, when the lens is focused at the infinity (*) mark.
For those who want to know, the focal length of a 'standard' lens for any film format approximately equals the diagonal measurement of the format-- that is the length from one corner to the opposite corner of the film. In the case of 35mm film format for instance, this works out to about 45 mm.
A lot of cameras are being sold now with a zoom lens which covers a range of focal lengths from a bit less than 'standard', say, 35mm, to a bit more than standard, perhaps 70 or 80mm. This actually gives the photographer a bit of flexibility to exactly compose the subject as desired.
When wanting to increase that range (if the camera permits interchanging the lens), there are quite an array of lenses of different focal lengths for many modern cameras.
There are telephoto lenses, suitable for taking distant portraits or pictures of timid animals, or sports and actions shots. The telephoto focal lengths for a film format cover from about 1.5 to 2 x the standard lens up to as much as 20 x or more. So for a 35mm format camera, telephoto lenses start at about 80 mm and can be as long as 2000 mm.
Then there are wide-angle lenses, which are often used for covering wide landscapes or buildings, or capturing large groups of people. Generally, wide-angle focal lengths start from about 3/4 the focal length of the standard down to as little as 1/5 of the standard focal length. Again using 35mm format as an example, for this format wide-angle lens focal lengths would range from about 35mm down to as little as 8 mm.
Zoom lenses are becoming more and more popular for their ability to provide a range of focal lengths in the one unit, sometimes covering from wide-angle to telephoto focal lengths. This is advantageous for saving weight and space in a camera bag instead of having to carry around and keep changing different lenses.
Other lenses are available for special applications such as macro / close-up, or for achieving 'perspective control' by allowing lateral manipulation of the lens components, just to mention a few.
In the next article, I will discuss Depth-of-Field.
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Submitted By
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David Barry |
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Description
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Photo enthusiast |
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Other Articles in this Category
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How To Understand Your Camera and Film 9: Filter Types
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How To Understand your Camera and Film 3: Lens Terms
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How To Understand Your Camera and Film 5: Film Types
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How To Understand your Camera and Film 1: Film Speed
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How to Understand Your Camera and Film 7: Depth of Field
by David Barry
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