5 tips on buying a camera lens (contd..)

Tip 1 (What are Canon's EF vs. EF-S lens): Deciphering what the acronyms written for the lens mean can be confusing for people who don't know what they mean. Till 2003, all the lens prepared by Canon were called EF (electrofocus); however, in 2003, Canon introduced the Digital Rebel series of cheaper DSLR's. For this new camera, there was a new lens introduced that was known as EF-S. All new Canon digital cameras are EF and EF-S compatible. However, the main difference between the EF and the EF-S lens are that EF-S lens have smaller mirror boxes, and smaller sensors. The EF-S lens work with the current range of Digital SLR's, but because of their smaller sensors, they will not work with any full frame cameras that Canon releases.

Tip 2 (Same lens works differently on film and digital cameras): Consider the above case again, where the EF lens will work on both film and digital cameras. However, the EF lens on a film camera will show more of the scene that a digital camera (except for a full frame digital camera).

Tip 3 (When the lens has the term full frame equivalent or 35mm equivalent): This term refers to the fact that most digital cameras have a sensor that is smaller than on a film camera, and as result, there is a factor known as the cropping factor. So a digital camera with a cropping factor of 1.6 will mean that a lens with a 60mm focal length will actually be the same as a lens of 96mm focal length on a film camera. Keep this calculation in mind when deciding to purchase a lens.

Tip 4 (Read the focal lenghts printed on the lens and the box): Many times, people are confused when they read all the acronyms printed on the lens (and on the lens box). One of these acronyms refers to the focal length, so a lens with the text 80-200mm refers to a zoom lens with the focal lenght between 80mm and 200mm

Tip 5 (Aperture printed on the lens): Lens also have the aperture printed on them. If you don't have a high end lens, it is likely that your lens will not have the same maximum aperture at all zoom lengths, it is more likely that your zoom lens has the following text: 1:2.8-4.5. This means that the lens will have an aperture opening of 1/2.8 at the mimimum zoom, and 4.5 at the highest zoom, which means that you will have less light, and is certainly not a fast lens.