GLOSSARY^205
E–F
entrance pupil A virtual representation of a lens’s aperture opening, the entrance pupil is a mea-
sure of the angles that light will take on its passage through the aperture. It is of more practical con-
sideration in the shooting of panoramic photos, which are often taken as several shots using a
camera that pivots to take in the wide vista that is later pieced into a single wide photograph. A haz-
ard in panoramic photos is parallax error, caused when the camera does not pivot correctly about its
center of perspective. The error can cause an object as immobile as a fence post to appear twice in
the same photo, seemingly in different positions. To avoid parallax error, the camera must pivot on its
center of perspective, which coincides with the entrance pupil. (Writings on panoramic photography
often erroneously identify the center of perspective as a lens’s nodal point.)See also panorama
and nodal points.
EXIF (exchangeable image file) A file storage format used for images on flash memory cards
and digital cameras. EXIF files contain either JPEG compressed files or uncompressed TIFF files along
with extensive information about a camera’s settings when a photo was taken.
exposure The amount of light used in a photograph, based on the aperture and how long the
shutter stays open.
exposure compensation The capability to automatically change exposure by one or more
stops to lighten or darken the image.
filter A mathematical formula applied to a digital image. Most image editors offer filters to correct
flaws in exposure, color, sharpness, and other blemishes. See also plug-in.
fish-eye lens An extremely wide-angle lens that can take in a view as wide as 180°. The result is
often a circular image.
fixed focus A lens made to permanently focus on the most common range, from a few feet to
infinity. The focus is usually not as sharp as that obtained with a variable focus lens.
flash A short, brilliant burst of light.
flash, fill Flash used to fill shadows caused by overall bright lighting.
flash, high-speed In ordinary flash photography, the flash is synchronized to fire when the first
shutter curtain is fully open and before the second curtain starts to close. High-speed sync extends the
flash duration, making flash synchronization possible when using fast shutter speeds that form a slit
between the first and second curtains when they are opening/closing simultaneously.
flash, modeling A longer flash fired before photographs are taken to determine how the place-
ment of the flash will affect light balance and shadows.
flash, multiple A lighting setup using several flash units that may be wired to the same camera,
or that are activated by radio signals or by the burst of light from a central flash gun.