Canon® EOS Digital Photography Photo Workshop

7.3. CONSIDER A FILTER

Using filters is a great way to extend the functionality of your lens, whether you're adding a special effect, eliminating hazy conditions, or optimizing sunlight using polarization (filters are covered in more detail later in the chapter). However, the way you attach a filter to your camera lens varies depending on the lens size.

For most lenses up to about 200mm in focal length, you can purchase a screw-mount filter that attaches to the end of your lens. You purchase filters according to the size (measured in millimeters) of the diameter of your lens — not the focal length. For example, if you're buying a haze filter for the Canon EF 24-70mm f/2.8L USM, the size for a filter for that lens is 77mm, which is the diameter of the camera's lens at the end where threads exist to attach the filter.

NOTE

For a detailed look at the specifications on macro lenses, see Chapter 6.

For very large lenses, such as the Canon EF 500mm f/4L IS USM, the diameter at the front of the lens is far too large (5.8 inches) to accommodate a screw-mounted filter. Instead, these lenses include a special drop-in compartment close to the rear of the lens that holds the filter (usually 48 or 52mm size) and a filter holder.

Other types of filter holders for big lenses, which are often included/integrated with the lens, support square filter gels, which are optical gel materials that you simply slip into the holder to create the desired effect.

NOTE

You can also mount larger lenses to ...