Canon® EOS 30D Digital Field Guide

Chapter 6. Selecting and Using Lenses

In This Chapter

• Understanding the focal length multiplication factor

• Lens choices

• About zoom lenses

• About single focal length lenses

• Using wide-angle lenses

• Using telephoto lenses

• Using normal lenses

• Using macro lenses

• Extending the range of any lens

The lens is the eye of the camera, so don't underestimate the importance of quality lenses. With a high-quality lens, pictures have stunning detail, high resolution, and snappy contrast. Conversely, low-quality optics produce marginal picture quality.

This chapter takes a look at the lenses available to help you make decisions about which additional lenses you'd like to add to your system for the type of photography you most enjoy.

Understanding the Focal Length Multiplication Factor

The EOS 30D image sensor is 1.6 times smaller than a traditional 35mm film frame. It is important to know the sensor size because it not only determines the size of the image, but it also affects the angle of view of the lenses you use. A lens's angle of view is how much of the scene, side-to-side and top-to-bottom, that the lens includes in the image.

The angle of view for all lenses you use on the Canon EOS 30D is narrowed by a factor of 1.6 times at any given focal length, giving an image equal to that of a lens with 1.6 times the focal length. That means that a 100mm lens on a 35mm film camera becomes the equivalent to a 160mm on the EOS 30D. Likewise, a 50mm normal lens becomes the equivalent of an 80mm lens, which is equivalent ...