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Friday, June 18, 2010

Focal Length: Quick Guide


Focal length is the distance from the film to the optical centre of the lens when the lens is focused on infinity. On most adjustable cameras it is marked in millimetres on the lens mount


If you are planning to buy a point and shoot camera or also called as compact digital camera, you do not only consider the megapixel size of imaging processor but also the focal length of the zoom lens. Focal length is just as essential as the image processor.

If the camera is a 35 mm, 50 mm lens would be the point of reference. A 50 mm lens on a 35 mm camera is called normal or standard lens. A 50 mm lens gives you real close to what your eyes sees. Meaning to say that the angle of coverage of a 50 mm lens will give you a picture of what you see without scanning your eyes side to side.

If you have a lens that is lower than the 50mm lens, it will put more of the scene your are looking at than what your eyes normallly see without scanning your eyes side to side. Its like being able to move back from what you are trying to take a picture without actually having to move backward. This type of lens is called wide angle lens.


If the lens has a number higher than 50mm, it covers less of the subject. Its as if you are moving closer to the subject. This kind of lens is called telephoto lens.

A zoom lens that covers 38mm to 70mm for instance gives you slightly wider angle of view than you see normally and slightly less than you normally see plus everything in between. Its just like moving closer or farther to the subject or scene.


A lens that has a higher number than 50, will cover less of the subject. Just like moving closer to it. A zoom lens that covers 38mm to 70mm for example gives you slightly wider angle of view than you see normally and slightly less than you normally see plus everything in between. It’s like being able to move forward to get closer or backwards to get more of the scene into your picture.

Certain focal lenghts lend themselves to certain subjects, like a 70 mm lens is best for portraits, while a 150 mm lens is just good for sports where you can zoom the lens to get closer to the actioin. A 28 mm lens on the other hand works well when shooting landscape.

Focal length has an effect on the depth of field – the distance between the nearest and furthest sharp objects in a photograph. A wide-angle (or short) lens will provide a greater depth of field than a long lens.

Source: Daryl DeVault.www.warehousephoto.com.2008

1 comments:

Ron said...

Excellent information on Focal Legnth.

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