Introduction to Lenses

Most digital cameras have a fixed zoom lens that can't be removed or replaced.
One big advantage is that the camera is sealed so no dust can get on the image sensor.

Digital SLR cameras have removable lenses so you can change them when circumstances dictate.





Lens Information:

Many lenses display information that is useful in your photography. Be sure to take the time to read it and any printed information that came with the lens.

Information around the lens may include:

The focal length of the lens or the zoom range in mm. Here the range of a zoom lens is 6.0-72.0mm. On fixed lens cameras the zoom range is often given as a multiplier. For example, 6.0-72.0mm is 12x.

The maximum aperture or aperture range on a zoom lens. A lens' maximum aperture is determined by dividing the actual diameter of the aperture opening into the focal length of the lens. That's why the aperture might change from f/2.8 when zoomed in, to f/3.7 when zoomed out. Larger maximum apertures let you use faster shutter speeds to freeze action, but can add dramatically to the cost of a lens.

The size of filters or other accessories that can be screwed into the threads. The diameter is usually preceded with the symbol f as in f85mm.

David B Flynn.