Aperture: The lens opening formed by the iris diaphragm inside the
lens. The size is variable and is adjusted by the aperture control.
Aperture-priority mode: an automatic exposure system in which the
photographer set the aperture (f-stop) and the camera selects a
shutter speed for normal exposure.
ASA (ISO): the sensitivity of the film or CCD to light, ranging from
slow (ASA 50) to fast (1600). The higher the number, the more
sensitive to light, but the more grain or noise in the image. The
rating number doubles as the sensitivity doubles.
Automatic exposure: A mode of camera operation in which the camera
automatically adjusts either the aperture, the shutter speed, or both
for normal exposure.
Bracketing: Taking several photographs of the same scene at different
exposure settings, some greater than and some less than the setting
indicated by the meter, to ensure a well-exposed photograph.
Close-up: A larger-than-normal image obtained by using a lens closer
than normal to the subject.
Color Temperature: Description of the color of a light source measured
on a scale of degrees Kelvin.
Contrast: The difference between the light and dark parts of a scene
or photograph.
Contrasty: Having a greater than normal differences between light and
dark areas. The opposite of flat.
Crop: To trim the edges of an image, often to improve the
composition. Cropping can be done by moving the camera position while
viewing a scene, by adjusting the enlarger or easel during printing,
or by using a crop tool in Photoshop.
Diffused light: Light that has been scattered by reflection or by
passing through a translucent material above the negative.
Direct light: Light shining directly on the subject and producing
strong highlights and deep shadows.
Dodge: To lighten an area of an image by blocking light (or using a
dodge tool in Photoshop).
Environmental portrait: A photograph in which the subject's
surroundings are important to the portrait.
Exposure: The amount of light reaching the film/CCD controlled by the
combination of aperture and shutter speed.
Exposure meter (light meter): a device that measures tha amount of
light and provides aperture and shutter speed combinations for correct
exposure. Exposure meters may be built into the camera or as separate
instruments.
Exposure mode: The type of camera operation (manual, shutter-priority,
aperture-priority) that determines which controls you set and which
ones the camera sets automatically. Some cameras operate in only one
mode. Others may be used in a variety of modes.
Flat: Having less-than-normal differences between light and dark
areas. The opposite of contrasty.
Focal length: The distance from an internal part of a lens (the rear
nodal plane) to the film/CCD plane when the lens is focused on
infinity. The focal length is usally expressed in millimeters (mm) and
determines the angle of view (how much of the scene can be included in
the picture) and the size of the objects in the image. A 100mm lens,
for example, has a narrower angle of view and magnifies objects more
than a lens of a shorter (50mm) focal length.
Focus: The point at which the rays of light coming through the lens
convertge to form a sharp image.
F-stop: (f-number) A numerical designation (f/2, f/2.8) indicating the
size of the aperture (lens opening).
Grain: The particles of silver that make up a photographic image.
Gray card: A card that reflects a know percentage of light falling on
it. Often, has a gray side reflecting 18 percent and a white side
reflecting 90 percent of the light. Used to take accurate exposure
meter readings. Meters based their exposures on a gray tone of 18
percent reflectance.
Highlight: A very light area in a scene, print, or transparency. A
high value.
Infinity: The farthest distance marked on the focusing ring of the
lens, generally about 50 ft. When the camera lens is focused on
infinity, all objects at that distance or farther away will be sharp.
ISO (ASA): the sensitivity of the film or CCD to light, ranging from
slow (ASA 50) to fast (1600). The higher the number, the more
sensitive to light, but the more grain or noise in the image. The
rating number doubles as the sensitivity doubles.
Latent image: An image formed by the changes to the silver halide
grains in photographic emulsion upon exposure to light. The image is
not visible until chemical development takes place.
Manual exposure: A non-automatic mode of camera operation in which the
photographer set both the aperture and the shutter speed.
Middle gray: A standard average gray tone of 18 percent reflectance.
See gray card.
Midtone: An area of medium brightness, neither a very dark shadow nor
a very bright highlight. A medium gray tone in print.
Negative: An image with colors or dark and light tones opposite of
those in the original scene.
Open-up: To increase the size of the lens aperture. The opposite of
stop down.
Overexpose: To expose to too much light, producing a lighter than
normal image.
Panning: To move the camera during the exposure in the same direction
as a moving subject. The effect is that the subject stays relatively
sharp and the background becomes blurred.
Perspective: The optical illusion in a 2-dimensional image of a
3-dimensional space suggested primarily by converging lines and the
decrease in size of objects farther from the camera.
Plane of critical focus: The part of a scene that is most sharply
focused.
Programmed automatic: A mode of automatic exposure in which the camera
sets both the shutter speed and the aperture for a normal exposure.
Shutter: A device in the camera that opens and closes to expose the
film to light for a measured amount of time.
Shutter-priority mode: An automatic exposure system in which the
photographer sets the shutter speed and the camera selects the
aperture (f-stop) for normal exposure.
Shutter release: The mechanism, usually a button on the top of the
camera, that activates the shutter to expose the film.
Shutter speed control: The camera control that selects the length of
time the film is exposed to light.
Single-lens-reflex (SLR): A type of camera with one lens which is used
both for viewing and for taking the picture. A mirror inside the
camera reflects the image up into the viewfinder. When the picture is
taken, this mirror moves out of the way, allowing the light entering
the lens to travel directly to the film/CCD.
Stop down: To decrease the size of the lens aperture. The opposite of
open up.
Tripod: A 3-legged support for a camera.
Underexpose: To expose to too little light, producing a darker than
normal picture.
Zoom lens: A lens with several moving elements which can be used to
produce a continuous range of focal lengths.