Lens focal length is the most important characteristic of a lens. One of the prime advantages of a single·lens reflex camera or a view camera is the interchangeability of its lenses; the reason photographers own more than one lens is so that they can change lens focal length. …
PDF: Lens Focal Length, The Basic Difference Between Lenses
Normal Focal Length The Most Like Human Vision
A lens of normal focal length, as you might expect from the name, produces an image on film that seems normal when compared with human vision. The image includes about the same angle of view as the human eye sees clearly when looking straight ahead, and the relative size and spacing of near and far objects appear normal. …
PDF: Normal Focal Length The Most Like Human Vision
Short Focal Length, Wide-Angle Lenses
Lenses of short focal length are also called wide-angle or sometimes wide-field lenses, which describes their most important feature they view a wider angle of a scene than normal. A lens of normal focal length records what you see when you look at a scene with eyes fixed in one position. …
PDF: Short Focal Length, Wide-Angle Lenses
Long Focal Lenght, Telephoto Lenses
A lens of long focal length seems to bring things closer, just as a telescope does. As the focal length gets longer, less of the scene is shown (the angle of view narrows), but what is shown is enlarged (the magnification increases). …
PDF: Long Focal Lenght, Telephoto Lenses
PDF: Minimum focusing distances for medium telephoto lenses
Zoom, Macro, and Fisheye Lenses
In addition to the usual range of short-, long-, and normal-focal-length lenses, other lenses, such as those shown here, can view a scene in a new way or solve certain problems with ease. …
PDF: Zoom, Macro, and Fisheye Lenses
Variable Focal Length Lens, The Zoom
The zoom, or variable focal length lens offers several technical and visual advantages. To begin with you can just take out one lens instead of two or three of varying focal lengths. And within the limits of its zoom range you can continuously vary the size of the image-enlarging or reducing it until the right parts of the subject exactly fill the frame. …
PDF: Variable Focal Length Lens, The Zoom