Tuesday, December 13, 2011

Lens Terms

You may have come across different lens terms and not been sure what they all mean. Below, we define these common terms for you.


PRIME LENS:  A lens with a fixed focal length. When you look through it, you can't change the magnification. Examples: 28mm, 50mm, 85mm, 135mm. Also referred to as a Fixed Focal Length Lens.

ZOOM LENS:  Also referred to as a Variable Focal Length Lens. When you look through it, you can change the magnification. Examples: 18-55mm, 24-70mm.

TELEPHOTO LENS:  A lens in which the physical length of the lens is shorter than the focal length. Often long-focal-length lenses (ex. 100mm, 200mm, 300mm) are referred to as telephoto lenses (although not always correct).

FAST LENS:  A lens that has a large aperture which allows you to take photos in low lighting without a flash. Examples: 50mm f1.4, 85mm f1.2. Likewise, if someone is talking about "lens speed", they are referring to the maximum aperture on that lens. You will also hear the term "slow lens" which is a lens with a smaller maximum aperture (usually above f2.8).

MACRO LENS:  A lens that allows you to focus much closer to the subject (than a non-macro lens). Examples: 50mm 2.5 macro, 60mm 2.8 macro, 100mm 2.8 macro.

WIDE ANGLE LENS:  A lens that will make things appear further away than they do with normal vision, and will also allow you to cover a larger area in your photos. Used for indoor photography when space is limited, as well as outdoor photography when you need to capture a large area or landscape. Any lens with a focal length smaller that your camera's standard or normal lens would be consider to be wide angle. Example: 20mm.

FISHEYE LENS: A wide-angle lens that takes a hemispherical image. Produces a distorted image, convex in appearance, and covers a broad area of view. Focal lengths typically range from 16mm and lower. Examples: 8mm, 10mm. 

SOFT FOCUS LENS:  A lens that is designed to gently diffuse the overall image. Generally used when taking portraits. Example: 135mm 2.8 soft focus. Not to be confused with soft focus filters.

FLAT FIELD LENS:  A lens that is designed to give you extreme sharpness from edge to edge. Generally used in Macro lenses.

CURVED FIELD LENS:  The most common lens design used today. Sharp in the center, but tends to go softer as you reach the sides.

CAT LENS:  Also referred to as a mirror or reflex lens. Uses mirrors in it's design to make larger focal length lenses smaller, lighter, and less expensive. Has a fixed aperture.

PORTRAIT LENS:  A lens that gives the best perspective for taking portraits. This will vary depending on the camera that you're using. For example, if you're using a 35mm film camera, it would be an 85mm or 105mm lens. If you're using a 6x6 film camera, a 150mm would probably be your choice. Keep in mind that with a digital camera, there may be a magnification or crop factor, so the lens focal length choice might be a bit different.

STANDARD LENS:  Also referred to as a normal lens. This would be considered to be the lens that gives you about the same perspective as normal vision. Nothing would appear any closer (or further away) than you would see it with your normal vision. This focal length will change depending on which type of camera that you use. If using a 35mm film camera, a 50mm lens would be considered as the normal lens, while a 75mm or 80mm lens would be considered normal when using a 6x6 film camera. When using a digital camera, the magnification or crop factor must be considered when determining a normal lens.


- AZ