[edit]
Glossary
A quick glossary of photographic terms.
- Aperture
- The aperture is the hole through which light enters the camera. Combined with the shutter speed, the aperture controls the exposure of the film or sensor. Aperture is measured in f-stops. Smaller apertures (larger f-stops) tend to give a deeper depth of field.
- Bokeh
- The way in which out of focus light is rendered by a lens. Good bokeh is a smooth and natural looking fuzziness. Bad bokeh tends to create unpleasant artifacts. This page give a more complete definition, with examples of good and bad bokeh.
- Depth of Field
- Depth of Field refers to range of distances such that elements are in focus. An image with a narrow depth of field has a very small amount in focus. An image with a large depth of field has a lot in focus.
- Distortion
- As light passes through objects (such as the glass in lenses) it bends and changes direction. This can cause the image captured by the sensor or film to have a slight (or not so slight) difference from what the human eye perceives. Most noticably, straight lines may not appear straight in the image.
- f-stop
- The f-stop is the unit of measure for the aperture. The f-stop is the the size of the aperture expressed as a fraction of the focal length of the lens. This is why some zoom lenses have different minimum f-stops based on the amount zoom. An f-stop of f/16 (f being the focal length), means that a 200mm lens has an aperture openning of 200/16 = 12.5mm. A 18mm lens has an aperture openning of 18/16 = 1.125mm. For a given f-stop any lens, regardless of focal length, transits the same amount of light to the sensor or film.
- Focal Length
- The focal length is the distance from the front element of a lens to the sensor (or negative). The focal length can be used to describe the effect that the lens has on the produced image. A long focal length (say, 50mm and up) make objects look closer (like a telescope). Short focal lengths (24mm and smaller) capture a wider view, making object smaller. Lenses with short focal lengths are sometimes refered to as wide angle.
- Hyperfocal Distance
- The hyperfocal distance is the distance from the camera such that if the camera is focused at that distance everything from infinity to half way between the camera and the hyperfocal distance is in focus. There is a page dedicated to hyperfocal distance here.
- Macro
- Macro photography is taking pictures at very close distances to capture small objects on film. A strict definition of Macro photography often requires a particular ratio of life size to sensor size (that is, how big the object actually is to how big it appears on the sensor), often 1:1. Thus objects are captured life size on the sensor. However more commonly, macro simply refers to the ability to focus on objects very close to the lens of the camera. I have a page describing macro techniques here
- Pan Focus
- An image with pan focus has a both the foreground and background in focus. To achieve this effect you need a very large depth of field, usuaully achieved by using the hyperfocal distance.
- Shutter
- The shutter is the part of a camera that stops the light entering the camera from exposing the film. When the photographer wants to expose the film, the moves to allow the light into the camera.
- Shutter Speed
- The length of time the shutter is open, allowing light to enter the camera. Combined with the aperture, the shutter speed controls the exposure of the film or sensor. Shutter speed is usually measured in fractions of a second, such as 1/30s, 1/60s, etc.
- Vanishing Point
- When a 3D scene is captured as a 2D image, distance objects are smallers that nearby ones and objects that are equal distance apart, but further away are rendered as closer together. This creates the appearance that distance objects are shrinking and converging to a single point in the image. This point is called the vanishing point.
- Wide Angle
- A wide angle lens is a lens with a wide viewing angle. Wide angle lenses have a short focal length. There is a page dedicated to wide angle photography here.