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"F" terms

"f-number" to "Front lighting"

The bottom scale on this lens shows f-NUMBERS from ƒ/16 to ƒ/1.4.
The bottom scale on this lens shows f-NUMBERS from ƒ/16 to ƒ/1.4.

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f-NUMBER - (ƒ-number) A number that expresses a lens’ light-transmitting ability - i.e. the size of the lens opening, its aperture size. Usually found on the barrel of a lens, f-numbers indicate the size of the aperture in relation to the focal length of the lens. A smaller number indicates a larger lens diameter. ƒ/1.4 signifies that the focal length of the lens is 1.4 times as great as the diameter. All lenses set at the same f-number transmit the same amount of light.

ƒ-STOP - (f-stop or F/stop) A lens aperture setting calibrated to an f-number (see above). Each stop either halves or doubles the amount of light passing through the lens. So, an ƒ-stop of ƒ/16 lets through half the light that is allowed through when using ƒ/11.

FADE - The gradual loss over time of a photographic print's, transparency's or negative's density in silver, pigment or dyes.

FALLOFF - Decrease in the intensity of light as it spreads out from the source.

FAST FILM - High speed film, i.e. film that is more sensitive to light, meaning less light is needed to obtain a properly-exposed image.

FAST LENS - A lens that has an aperture that opens particularly wide, making it able to gather more light than a slower lens at its widest aperture.

FB - Fiber-based, as in "Fiber-based paper" (See below).

FEATHERING - The intentional gradual blurring of the edges of an image, resulting in "softer" gradated borders.

FIBER-BASED PAPER - Fiber-based photographic print papers consist of a paper base covered with a clear, hardened gelatin above the emulsion layer to protect it from damage during processing and afterwards. High quality exhibition or archive prints are typically made using FB paper, which require careful processing and delicate handling when wet. FB papers are easier to color and retouch than RC (resin-coated) papers.

FIELD - A term used in place of "Location" when the location is outdoors. It refers to photography away from a studio. Example: "We will be shooting in the field."

FIELD CAMERA - A type of camera, also known as the "baseboard" camera, is essentially a portable view camera, because it functions in much the same way and with similar controls and features and can be transported with relative ease into the "field" - i.e. outside the studio.

FILE FORMAT - The standard way in which a digital image is encoded for storage, dependent upon the proposed use of the image, such as print, email or web viewing. Various formats (e.g. .JPEG, .TIFF, .PSD, etc.) have different characteristics.

FILL FLASH - Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Fill flash is generally not intended to overpower another light source, but rather to bring out detail that would otherwise be lost in shadow. Also known as “flash fill” and “fill-in flash.”

FILL IN - (1) Noun: see "FILL LIGHT" below. (2) Verb: To use secondary illumination (typically artificial light such as flash), or a reflector or combinations of both, as fill light.

FILL LIGHT or "Fill-in light" - Secondary light from a lamp or reflector that illuminates shadow areas. Called "Fill flash" when the light source is a flash.

FILM - A transparent cellulose nitrate or cellulose actetate composition made in thin, flexible strips or sheets and coated with a light-sensitive emulsion for taking photographs.

FILM PLANE - The place in a camera where the film is located in readiness for it to be exposed to light.

FILM SOLARIZATION - See "Solarization" in this Glossary.

FILM SPEED - A measurement of film’s sensitivity to light, generally in numerical terms of an ISO exposure index - e.g. ISO 100. More sensitive (faster) films have higher ISO numbers and require less exposure in order to make a properly-exposed picture.

The FILTER selection available to photographers is tremendously wide.
The FILTER selection available to photographers is tremendously wide.

FILTER - There are two types of filter in photography:
(1) A photography filter is a transparent piece of tinted glass, plastic or gelatin, often but not necessarily disc-shaped, used to alter the color or character of light or to reduce the amount of light. Filters may be in the shape of discs, squares or rectangles. Filters are used in photography to change the appearance of a scene by emphasizing, eliminating or changing color or density, generally so that the scene can be recorded with a more natural look, on a particular film or a digital sensor.
(2) In image-editing programs such as Adobe Photoshop, the use of a digital filter applies a set of image characteristics to all or part of an image.

FILTER FACTOR - A number that indicates to what extent you must increase exposure when you use a particular filter (by multiplying the unfiltered exposure by the filter factor number). Filters absorb light. The filter factor allows you to compensate for this absorption. The amount of exposure compensation has been predetermined for every filter, and is expressed as a “filter factor” (sometimes also called an exposure factor, and also referred to as Exposure Magnification or EM values).

FILTER, LOW-PASS - In a dSLR, one or more low-pass filters are located in front of the imaging sensor to:
- allow the lowest-frequency waves through and cut off the highest, effectively reducing the amount of detail getting through to the sensor,
- resolve aliasing that causes jagged edges when photographing circular objects and diagonal lines, and
- protect the sensor from dust. Most have an anti-static coating to discourage dust from sticking.

FILTER SIZE - is determined by the inner diameter of the front of a lens, more specifically the threads into which a filter is screwed to attach it to the lens. A 62 mm filter screws onto a lens that has threads that have a diameter of 62 mm. Most filters and some lenses are inscribed with their filter size in millimeters.

FILTER SIZE, measured in millimeters, is inscribed on the filter (left) and sometimes on the lens (right).
FILTER SIZE, measured in millimeters, is inscribed on the filter (left) and sometimes on the lens (right).

FINDER - A shorter word to use when referring to a camera’s viewfinder.

FINE GRAIN DEVELOPERS - Film developers that minimize grain in the final image.

FINGERPRINT - An invisible identifier placed in a digital image file that is not affected by normal image editing and can be retrieved using software.

FIREWIRE - Also known as IEEE 1394. A computer connector that permits high-speed data transfer, including downloading from a digital camera. Data transfer is faster than USB. Accessories with FireWire capability can be plugged in and removed from the computer without having to turn off the computer. Firewire ports are usually found on high quality video and digital cameras.

FISHEYE - Describes an extreme wide-angle lens that has an angle of view exceeding 100 - sometimes more than 180 - and that renders a scene as highly distorted.

FIXATION - In negatives and prints alike, the conversion of unused silver halides to a soluble silver so that the image remains stable and unalterable when exposed to light. Also known as “fixing.”

FIXED FOCAL LENGTH - Also known as a "Prime lens." Fixed focal length describes a lens that has a focal length that is not adjustable; it's fixed. Such a lens cannot be zoomed.

FIXED FOCUS - Refers to a lens, the focus of which cannot be changed. Found in simple cameras, the focus is preset (or fixed) by the factory, usually at the hyperfocal distance, resulting in image sharpness for most common shooting conditions for snapshots.

FIXER or "Fixing bath" or "Hypo" - The chemical solution used for fixation. It removes any photo-sensitive silver-halide crystals that were not acted upon by light or by the developer.

FLARE can show up as a plain area of unwanted bright light or in shapes matching the aperture.
FLARE can show up as a plain area of unwanted bright light or in shapes matching the aperture.

FLARE - Light that doesn’t belong in an image, often taking the shape of the aperture, generally caused by shooting towards the light source. The source may appear in the image as a reflection from the interior of the camera or from the lens. Flare often results in an overall reduction of image contrast. Attaching a lens hood can help avoid flare.

FLASH - (1) A brief, sudden burst of bright light from a flashbulb or an electronic flash unit; (2) An artificial light source that provides brief, bright illumination of a subject in order to properly expose photographic film; (3) Often used in reference to the actual unit that produces the flash, as in "My flash is built into my camera."

FLASH BULB - A one-time-use glass bulb enclosing a pyrotechnic wire filament that burns out, generating a bright flash, when an electrical current is run through it.

FLASH CUBE - A cube-shaped unit containing four built-in flash bulbs that automatically rotates to the next usable bulb when one is fired. When all four flash bulbs have been fired, the unit is no longer usable, and is discarded. The flash cube is now obsolete, but was at one time a common flash accessory for many point-and-shoot cameras.

FLASH FACTOR - Also known as " Guide number," a number which serves as a guide to proper exposure when using flash. The number is based on a flash unit's light output and the film speed. When the flash factor is divided by the flash-to-subject distance, the correct aperture for proper exposure is determined. Flash factors may be quoted in meters or feet, according to which system is used for the measurement of distance.

FLASH FALL-OFF RATE - The rate at which the intensity of light from a flash diminishes over distance.

FLASH FILL - Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Better known as “fill flash” or “fill-in flash.”

FLASH MEMORY CARD - A camera's removable image storage device.

FLASH METER - Exposure meter designed to measure the light from electronic flash.

FLASHPATH - A 3.5-inch floppy disk drive that has been modified to accept SmartMedia memory cards so that data can be transferred (very slowly) to a computer through the computer's floppy disk drive.

FLASHPIX - A file format developed by Kodak and Hewlett-Packard to create image files in a digital camera. A compatible application is required to open Flashpix files.

FLASH POWDER - Used in the early days of photography, a mixture of metallic magnesium with an oxidizing agent that, when ignited, produces a bright flash of light.

FLASH SYNCHRONIZATION - Timing the triggering of the flash so that it fires only when the shutter is completely open, thereby ensuring complete exposure of the entire film frame.

FLASH TERMINAL - Electrical contact on a camera to which a cord that is connected to a flash unit is attached, permitting flash synchronization.

FLASH THROW - The flash's effective distance, that is, how far from the flash head its light adequately illuminates a subject for photography.

FLAT - A negative, slide or print that is too low in contrast due to a limited range in density.

FLAT LIGHTING - Illumination that provides little contrast on the subject and light or imperceptible shadows.

FLATTEN - Combining two or more layers of a digital image file, usually performed when all image manipulation changes have been completed and the assembled image is ready to be saved in a standard image format.

FLM - Focal Length Multiplier. Sometimes known as Focal Length Magnification. See "Format Factor" below.

FLOATING LENS - A lens element in a compound lens that changes its position as the lens is focused.

FLOODLIGHT - Continuous (non-flash), artificial light source, generally used in the studio for evenly-spread illumination. Also known as Photoflood or Flood lamp. Has a color temperature of 3400 on the Kelvin scale.

FOCAL LENGTH is the determination of the relative size of a lens.
FOCAL LENGTH is the determination of the relative size of a lens.

FOCAL LENGTH - Focal length is the distance between the focal point of a lens and the film plane when the lens is focused at infinity. It is used to designate the relative size and angle of view of a lens, expressed in millimeters (mm). A particular lens' focal length (e.g. 35mm, 50mm, 105mm, 600mm, etc.) can generally be found engraved or printed on the front of the lens.

FOCAL LENGTH MAGNIFICATION - Sometimes called FLM - See "Format Factor" below.

FOCAL LENGTH MULTIPLIER or FLM - See "Format Factor" below.

FOCAL PLANE - A camera's lens focuses light onto a specific plane where the film or sensor is located.

FOCAL PLANE SHUTTER - A camera shutter situated directly in front of the digital sensor or film, composed of an opaque curtain that contains a slit that moves directly across in front of the sensor or film, permitting light to strike the sensor or film. Some cameras employ two curtains.

FOCAL POINT - (1) The central or principal point of focus. This generally refers to the main subject of your picture - the photograph's center of interest. Also known as the Center of focus. (2) The optical center of a lens when it is focused on infinity.

FOCUS - (1) A point at which converging rays of light meet after being refracted or reflected. (2) Focal point of a lens. (3) The clear and sharply-defined condition of an image, as in “This image is in focus,” meaning it is sharp and well-defined. (4) Adjustment of the distance setting on a lens to obtain a sharply-defined image, as in to focus a camera.

FOCUSING - Adjusting a lens’ elements in relation to the film plane so as to obtain the required sharpness in the image.

FOCUSING HOOD - A cowl around focusing screens that shields the screen from light other than the light from the scene being photographed.

FOCUSING MAGNIFIER - A simple magnifying lens that enlarges the image on a focusing screen.

FOCUS LOCK - Also known as Focus Hold. A feature of a camera that permits the photographer to focus on an object and to "lock in" that focusing distance so it can be used to shoot another object. Focus lock is generally employed when an object that must be in focus is outside of the camera's autofocus sensor when framing the composition.

FOG or "Fogging" - Unwanted density in an image caused by accidental exposure to non-image forming light or X-rays, poor storage conditions or improper chemical processing.

FONT - A typeface's style, including the weight and size of the letters.

FORCED DEVELOPMENT - Another term for "Push-processing" - increasing development time of a film to "force" an increase in its effective speed.

FOREGROUND - The area of a scene that is closer than the subject.

FORMAT - The shape and size of a thing - used in photography principally in reference to small, medium and large format films and the photography equipment employed in handling each different film format (e.g. a "medium format" camera).

FORMAT FACTOR - Usually called the Crop Factor. A number used to multiply a lens's actual focal length to express how much of an apparent increase you can expect in the effective focal length of any traditional 35mm SLR lens you use on a dSLR camera. Also called the Focal Length Multiplier or FLM. Typical format factors are in the range 1.5 or 1.6 to 2.0.

FORMATTING - In a digital camera, formatting refers to the preparation of the memory card's contents to enable digital image data recording. Also known as initializing. When using a new memory card for the first time, you format it so the card can receive and store data from your digital camera.

FP - Refers to the Focal Plane of a camera.

FP HIGH-SPEED SYNC - Focal plane high-speed synchronization that occurs with a flash unit that emits pulses of extremely rapid flash illumination permitting light to pass through the shutter to the film or sensor at shutter speeds greater than the camera's standard sync speed.

FPS - Stands for "Frames per second" - See below.

The subject is shown in a FRAME created by FOREGROUND tree branches.
The subject is shown in a FRAME created by FOREGROUND tree branches.

FRAME - (1) generally refers to the boundaries or sides within which a picture is contained. (2) The visible boundaries of a camera’s viewfinder. (3) The area of a single exposure on a film. (4) An element in a scene, like a branch or doorway, that frames the subject. (5) A decorative border surrounding a print or digital image.

FRAMES PER SECOND - Frames per second (fps) refers to the number of pictures that a camera is able to take in a second. A point-and-shoot camera typically shoots one or two pictures per second. Higher-end single lens reflex (SLR) cameras have much greater performance, as many as five or more frames per second.

FRONTLIGHTING or Front lighting - Light illuminating the front of a subject - i.e. the side of the subject at which the camera is aimed.

FULL FRAME - A camera's sensor that has the same dimensions as a 35mm film frame - roughly 24mm X 36mm.

FULL-SIZED SENSOR - See Full Frame above.

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