process, such as the optical system, the emulsion, or
a developer.
FAST FILM–Photographic material of relatively high
sensitivity to light, having a high-exposure index.
(PIA)
FIELD–Scanning lines in one half of one video or
television frame. There are two fields (one odd, one
even) in a frame. One field equals 262.5 scanning
lines that create a total of 525 standard television
lines or one frame. Also known as the NTSC signal
(U.S. T.V. system).
FILM, COLORBLIND–Film which is sensitive only
to light of very short wavelengths (ultraviolet,
violet, and blue). (NMA)
FILM, PHOTOGRAPHIC, INFRARED–Film
coated with an emulsion especially sensitive to
infrared light.
FILM, PHOTOGRAPHIC, ORTHOCHROMATIC
(ORTHO)–A black-and-white film coated with an
emulsion that is sensitive to ultraviolet, violet, blue,
and green radiation. Not being sensitive to red, red
objects photographed with orthochromatic films are
rendered dark on the print.
FILM, PHOTOGRAPHIC, PANCHROMATIC
(PAN)–A black-and-white film coated with an
emulsion that is sensitive to ultraviolet, violet, blue,
green, and red radiation. The special sensitivity of
panchromatic films approach that of the human eye.
AI-7
FILM, PHOTOGRAPHIC, REVERSAL–A film
which after exposure is processed to produce a
positive image instead of the customary negative
image. Reversal films may be black and white or
color.
FILTER–Photographic. A layer of glass, gelatin, or
other material used to modify the transmitted light
selectively.
FILTER, NEUTRAL DENSITY–One not selective for
a certain portion of the spectrum but absorbing all
colors equally, thus reducing the intensity of light
without changing its chromaticity.
FILTER FACTOR–The number of times exposure
must be increased to compensate for light absorbed
by a filter.
FIXED FOCUS–The term applied to optical
instruments and photographic equipment that are
not provided with a means for focusing.
FIXER–A solution used to remove undeveloped silver
halides from photosensitized emulsions. The fixer
usually contains sodium or ammonium thiosulfate,
a hardening agent, and an acid or acid salt.
FIXING AGENT–A photographic chemical that
dissolves the silver halides not used for producing
an image to preserve the photograph from further
photographic effect upon subsequent exposure to
light. Common fixing agents are sodium thiosulfate
and ammonium thiosulfate.
FLARE–A defect of optical systems in which scattered
light resulting from reflections at optical surfaces,
the walls of the camera, or imperfections in the
optical parts, reaches the image plane and produces
an overall fog or flare spot that damages the
photographic quality of the resulting record.
FLASH, ELECTRONIC–A high-voltage light source
for photographic illumination, producing a
momentary flash of light of high intensity in an
atmosphere of gas enclosed in a tube that can be
used repeatedly. (PIA)
FLAT–An image is said to be “flat” if its contrast is too
low. Flatness is a defect that does not necessarily
affect the entire density scale of a reproduction to
the same degree. Thus a picture may be “flat” in the
highlight areas or “flat” in the shadow regions, or
both.
FLOATING LID–A lid designed to float on the top of
a photographic processing solution to reduce aerial
oxidation.
FLOODLIGHT –A photographic light used to produce
even lighting on large subjects. A floodlight spreads
light evenly over a wide angle, as distinguished
from a spotlight that concentrates light in a beam.
FLUID OUNCE–A unit of capacity in the Liquid
Measure System equal to 1.8 cubic inches; it is equal
to 29.57 milliliters.
FOCAL PLANE–The surface (plane) on which an axial
image transmitted by a lens is brought to sharpest
focus; the surface occupied by the light-sensitive
film or plate in the camera.
FOCAL POINT–The point at which converging rays
of light from a lens meet.
FOCUS–(l) The point at which rays of light passing
through different parts of a lens converge to form a
sharp image of the original. (2) (Verb) To adjust the
position of either the lens or focusing screen in a
