high key A description of a photograph with a
light overall tone.
histogram A basic bar graph that shows the
number of pixels that fall into each of the shades
from pure black to pure white. The histogram
view on most digital cameras shows the values of
the red, green, and blue color channels as well as
the overall tone of the image.
hot shoe The camera mount on top of the
camera viewfinder that accepts flash accessories.
Each camera manufacturer produces different
flash accessories, and those that are made for one
brand of camera usually do not work on another
camera brand’s body.
interval timer A device that triggers the
shutter release at predetermined intervals, allow-
ing for multiple images to be taken automatically
over a period of time. These timers are especially
useful in time-lapse photography where you need
a series of images to be taken over a set length of
time.
ISO International Organization for
Standardization. An international body that
sets standards for film speeds. The standard is also
known as ISO 5800:1987 and is a mathematical
representation for measuring film speeds. The
ISO setting on the dSLR describes the sensitivity
to light; the higher the number the more the sig-
nal is amplified and the more sensitive to light
the sensor appears.
ISO sensitivity A rating that measures the light
sensitivity of image sensors in digital cameras,
using the standards set for film. Each doubling of
the ISO makes the sensor twice as sensitive to
light, meaning that for practical purposes, an ISO
rating of 200 needs twice as much light as a rating
of ISO 400.flash A device that produces a short, bright
burst of artificial light. The word flash can be used
to describe the unit producing the light or the
actual light.
flash exposure compensation An adjustment
that changes the amount of light produced by a
flash, independent of the exposure settings.
flash sync The method by which the flash is
fired at the moment the camera shutter is opened.
flat A description of an image or scene that has
very little difference between the light values and
the dark values. This also describes an image or
scene with low contrast.
focal length The distance from the optical
center of the lens when it is focused at infinity
to its focal plane (sensor), described in millime-
ters (mm).
focal plane The area in the camera where the
light passing through the lens is focused. In digi-
tal cameras, this is the image sensor.
focus The adjustment of the lens to create a
distinct and clear image.
front lighting A method of lighting where
the main light is placed directly in front of the
subject.
f-stop A measure of the opening in the dia-
phragm that controls the amount of light travel-
ing through the lens. See also diaphragm.
HDR High Dynamic Range photography is a
method of combining differently exposed images
of the same scene to create a single image with a
greater tonal range than a regular photograph.
high contrast A description of an image or
scene where the highlights and shadows are at
the extreme differences in brightness.