Examples of Different Angles of View

All of these images were taken from the same distance from the subject, but using different lenses of varying focal lengths. Although the distance to the subject remains the same, the angle of view is radically different between each of these examples. All pictures were taken using a Panasonic AG-DVX100A, the M2 from Redrock Microsystems, and 35mm motion picture camera prime lenses.

Figure 12 was taken with a 28mm Zeiss ZF lens.

Figure 2 was the exact same distance from the subject, but taken with a 50mm Zeiss ZF lens (same setup).

Figure 3 A 100mm Zeiss ZF lens was used here, again at the same distance to the subject

As you can see, the images become progressively narrower in their angle of view as the lens lengths increase. You will also notice that in Figure 4 only the flower is in focus while in Figure 1 much of the image seems to be in acceptable focus. (Read the article on Dept of Field for an explanation of how this works.)

There is a similar effect of using your zoom lens on your DV or HD camera. By zooming in, the focal length increases, and results in an image similar to Figure 4. By zooming out the focal length decreases and results in an image similar to Figure 1. If this is the case, why not simply use a zoom lens? While having one lens makes the shoot somewhat simpler, there are tradeoffs. Zoom lenses tend to be "slower" than primes, meaning the maximum aperture is generally smaller than equivalent focal length primes. This, of course, requires more light. The other typical weakness in zooms is they usually "breathe". This means that when a rack focus is performed, the image size can change during the rack. This can happen with fixed focal length lenses designed for still cameras as well. Since still camera can't record a focus rack, the breathing is not figured in when the lens is designed. In summary, the benefits of using 35mm fixed length (prime) lenses are:

• Faster lenses (i.e., able to open the aperture more, resulting in more light)
• No lens breathing problems during focusing
• Shorter Depth of Field