Canon® EOS 40D Digital Field Guide

Chapter 6. Selecting and Using Lenses

In This Chapter

• Understanding the focal length multiplication factor

• Lens choices

• Zoom versus prime lenses

• Canon lens terminology

• Using wide-angle lenses

• Using telephoto lenses

• Using normal lenses

• Using macro lenses

• Using tilt-and-shift lenses

• Using Image-Stabilized lenses

• Exploring lens accessories

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. And as most photographers know, over time your investment in lenses far exceeds the money invested in the camera body. For these reasons, making studied decisions on lens purchases pays off for years to come in getting great image sharpness and quality.

This chapter looks at the lenses available to help you make decisions about lenses you can add to your system to enhance the type of photography you most enjoy.

Understanding the Focal Length Multiplication Factor

The 40D 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 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 40D is reduced by a factor of 1.6 times at any given focal length, ...