Understanding Camera Lens

1801 Words4 Pages

UNDERSTANDING CAMERA LENSES
Understanding camera lenses can help add more creative control to digital photography. Choosing the right lens for the task can become a complex trade-off between cost, size, weight, lens speed and image quality. This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number.
LENS ELEMENTS & IMAGE QUALITY
All but the simplest cameras contain lenses which are actually comprised of several "lens elements." Each of these elements directs the path of light rays to recreate the image as accurately as possible on the digital sensor. The goal is to minimize aberrations, while still utilizing …show more content…

Wide angle lenses have short focal lengths, while telephoto lenses have longer corresponding focal lengths.
Many will say that focal length also determines the perspective of an image, but strictly speaking, perspective only changes with one's location relative to their subject. If one tries to fill the frame with the same subjects using both a wide angle and telephoto lens, then perspective does indeed change, because one is forced to move closer or farther from their subject. For these scenarios only, the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
Perspective control can be a powerful compositional tool in photography, and often determines one's choice in focal length (when one can photograph from any position).
The following table provides an overview of what focal lengths are required to be considered a wide angle or telephoto lens, in addition to their typical uses. Please note that focal lengths listed are just rough ranges, and actual uses may vary considerably; many use telephoto lenses in distant landscapes to compress perspective, for …show more content…

These aperture ranges therefore refer only to the range of maximum aperture, not overall range. A range of f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully zoomed out) to f/3.0 (at full zoom). The primary benefit of having a zoom lens with a constant maximum aperture is that exposure settings are more predictable, regardless of focal length.
Also note that just because the maximum aperture of a lens may not be used, this does not necessarily mean that this lens is not necessary. Lenses typically have fewer aberrations when they perform the exposure stopped down one or two f-stops from their maximum aperture (such as using a setting of f/4.0 on a lens with a maximum aperture of f/2.0). This *may* therefore mean that if one wanted the best quality f/2.8 photograph, a f/2.0 or f/1.4 lens may yield higher quality than a lens with a maximum aperture of f/2.8.
Other considerations include cost, size and weight. Lenses with larger maximum apertures are typically much heavier, larger and more expensive. Size/weight may be critical for wildlife, hiking and travel photography because all of these often utilize heavier lenses, or require carrying equipment for extended periods of

Open Document