Help on Normal, Camera Lens vs Other?

Question

I'm getting more into digital photography. Currently I have a Canon XTi with an 18-55 mm lens. I have seen lens called, Normal Lens. When would these be practical to use and why?

Like a 28mm or 50mm lens.

Answer 1

When you say normal, do you mean lenses that have a focal length that's consider "Normal" (as opposed to wide or telephoto, traditionally 50mm in SLR), or do you mean a lens that does not zoom (ie, only 50mm instead of 18-50mm)?

If you're asking about a "Normal" focal length, these are lenses that are neither telephoto nor wide-angle -- traditionally, 50mm. They tend to have the similar perspective as the human eye, and thus make up the brunt of general photographic shots. The "Normal" lens is seen as the standard lens for a camera that will allow you to make about 85% of all your photos. As lenses diverge from 50mm, they tend to become more and more specialized, and also more expensive . Lenses today are still marked for their focal length equivalence on a 35mm camera, even if they can only be used on digital cameras such as your XTi. The Rebel and ##D (ex, 40D) series from Canon have a sensor that's smaller than a piece of 35mm film, and thus, for physics reason that I won't get into, they have a lens conversion factor of 1.6x. This means that for every lens that you put on your camera, you should multiply the focal length of the lens to get the effective focal length on your digital camera. Thus, on a digital camera, a 50mm lens is actually an 80mm lens, pushing it into the portrait or short telephoto range. A "Normal" lens on the XTi will be a 30mm or 35mm lens (35mm x 1.6 = ~56mm)

If by a normal lens, you mean a lens that does not zoom, such as a 30mm lens as opposed to an 18-50mm lens, then this is called a prime lens. Prime lenses are almost always smaller and of much greater optical quality than similarly-priced zoom lenses. This is the case because the lens can be optimized to work for one focal length as opposed to a zoom lens where it has to work over a range of focal lengths. The trade off is, of course, the inability to zoom with the lens -- you'll never be able to make the subject any bigger or smaller in the frame without getting closer or backing up. As I don't mind switching lenses, virtually all of the lenses that I use are primes. To me, I just feel that I get better color and contrast through these lenses as compared to my zooms of similar focal length.