- The aperture is the opening in the lens that allows light to
strike the film. The larger the aperture, the more light comes
through, however at large apertures depth
of field and resolution are reduced. Aperture is measured by
f-stops; the bigger the f-stop number, the smaller
- Cutting away the outer parts of an image to rearrange the elements
that remain. May be done digitally or in the darkroom.
- Depth of Field
- The distance from the foremost element of an image that is in
sharp focus to the rearmost element also in sharp focus. Depth
of field is increased with smaller apertures (higher f-stops)
or at lower magnifications.
- A part of the lens that reduces the amount of light that reaches
the film. In modern cameras, the diaphragm is held open while
looking through the viewfinder and closes only for the instant that
the picture is taken. The amount that the diaphragm is opened
or closed is measured by the f-stop.
See also aperture.
- The amount of light that reaches the film. Exposure is
determined by aperture and shutter
- A measurement of the aperture of a
lens. Smaller f-stops (f 2.8) let more light
in than larger f-stops (f 16) and allow faster
shutter speeds to be used. Larger f-stops give better
resolution and depth of field, however.
- A physical medium for making images. Film is coated with
photosensitive chemicals that are changed when exposed to
light. Processing makes these
changes permanent and visible. Negative
film forms transparent images that have reversed colors; they
are used when a final printed image is desired. Positive, or slide
films, form normal, transparent images that can be
projected. Films vary in their sensitivity to light; this is
measured by ISO numbers. More sensitive
films have higher ISO numbers, but also larger grain,
and thus may not have as good resolution as slower films.
- The rectangular border around an image; the
rectangular "footprint" of the the image; a single image
on a roll of film.
Grain The size of the
chemicals which record the light on the surface of the film. Larger
grain leads to a "fuzzier" picture.
ISO Short for
"International Standards Organization", the agency that determined
standards for film speed. Used as an abbreviation for film
speeds. Most consumer films have ISO's between 50 and 3200.
Digital cameras often have ISO equivalent settings. Faster ISO
ratings allow for faster shutter speeds and/or smaller apertures.
Faster ISO ratings usually mean more grain in film images and more
noise in digital images. Used to be called ASA.
When developed, the colors are reversed on negative film. This
film is then used to make a positive print.
individidual units or "dots" of a digital image.
- The ability to distinguish between two
points. The closer together the points are, the greater the
The length of time light is allowed to strike the film or imaging chip.
- In a camera: using a lens with varying focal lengths to change
perspective. Zooming in means using a longer focal length to
reduce the angle of view and make objects appear larger; zooming out
means using a shorter focal length to widen the angle of view and
make objects appear smaller (though more of them fit in the
image). On a computer: Zooming means to increase or
decrease the viewed size of the pixels that make up the image.