Friday, July 18, 2014

L is for Lens

L is for Lens

A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing images checmically or electronically.

Aperture and Focal Length
          Two fundamental parameters of an optical lens are the focal lenght and the maximum aperture. The lens's focal length dtermines the magnification of the image projected onto the image plane, and the aperture is the light intensity of that image.

Focal lengths are usually specified in millimeters, but older lenses might be marked in centimeters or inches. For a give film or sensor size, specified by the length of the diagonal, a lens may be classified as a:

  • Normal Lens: angle of view of the diagonal about 50 degrees and  a focal length aprroximately equal to the image diagonal.
  • Wide-angle Lens: angle of view wider than 60 degrees and focal length shorter than normal.
  • Long-focus Lens: any lens with a focal length longer than the diagonal measure of the film or sensor. Angle of view is narrower. The most common type of long-focus lens is the telephoto lens, a design that uses special optical configurations to make the lens shorter than its focal length.

DID YOU KNOW?: The widest aperture lens in history of photography is believed to be the Carl Zeiss Planar 50mm f/0.7, which was designed and made specifically for the NASA Apillo lunar program to capture the far side of the moon in 1966. 

Types of Lenses

*Wide-Angle* Cannon 28mm f/2.8 IS USM
Wide-ange Lens: focal length range from 21-35mm. With the advent of digital cameras, and the APS-C format, camera manufactures have also started producing specific lenses for this format. Wide-angle lenses crop frame DSLRs range from 10-24mm, with a few going down to super wide 8mm. These lenses are mostly used for photographing landscapes and srchitecture.
*Standard* Nikon 50mm f/1.8G AF-S

Standard Lensfocal length range from35-70mm. The most common standard lens is a fixed 50mm lens. These lenses are mostly use for documentary and street photography.

*Medium Telephoto* Zeiss Planar 85mm f/1.4 ZE
*Telephoto* Mamiya 7 150mm f/4.5
Medium Telephoto: focal length range from 80-135mm. Fixed lenses at these lengths produce ideal framing for head and shoulders shots perfect for portrait photographers.

Telephotofocal length range from 135mm-300mm. Traditionally used for sports and wildlife photography, but there essential function is to bring distant objects closer.

*Specialist* Lensbaby 12mm Fisheye Optic
Specialist Lens: there are a variety but here are the most common...

     - Super Telephoto: a focal length of more than 300mm and are used by dedicated sports and wildlife pjotographers.
     - Marco: able to focus closer to an object ofering 1:1 ratio and are used for still-life photography of small objects.

     - Fisheye: are on the edge of wide-angle lense and give a disorted view of the subject matter. the center of the image is magnified, and objects diminsh in size in all directions around it.

If you have trouble picking out the type of lens that will best capture your photograph just think about what types of pictures you like to take. That will probably narrow down your search.