Film Photography Glossary

Plain-language definitions of the terms you'll meet shooting, developing and printing film. Where a term has a full guide, the definition links to it.

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120 film

The medium format roll film in widest use today: about 61mm wide, paper-backed, with no sprocket holes. Depending on the camera it yields 15 or 16 frames of 6x4.5, 12 of 6x6, 10 of 6x7 or 8 of 6x9. Read the guide: Film Formats Explained

220 film

A roll film the same width as 120 but twice as long, with paper leader and trailer only, so it gives twice as many frames. It is no longer manufactured. Read the guide: Film Formats Explained

35mm film

Film 35mm wide with sprocket holes along both edges, loaded in a light-tight cassette. The standard frame is 24x36mm, and rolls hold 24 or 36 exposures. Also called 135 film. Read the guide: Film Formats Explained

4x5

The most common large format sheet film size, 4x5 inches, loaded one or two sheets at a time into film holders for a view or press camera. Read the guide: Film Formats Explained

8x10

A large format sheet film size, 8x10 inches. Usually contact printed, since the negative is already the size of a finished print. Read the guide: Film Formats Explained

A

Acutance

How sharply an edge is rendered between light and dark areas of an image. High-acutance developers such as Rodinal increase apparent sharpness, often at the cost of more visible grain. Read the guide: Black and White Developers

Agitation

Moving developer over the film during processing, by inverting or rotating the tank, so fresh chemistry reaches the emulsion evenly. Too little causes uneven development; too much raises contrast and can cause surge marks. Read the guide: Developing Black and White Film at Home

Alternative process

Any photographic printing process other than modern silver gelatin or color papers, usually hand-coated: cyanotype, salt print, Van Dyke brown, platinum and palladium among them. Read the guide: Alternative Processes

Aperture

The adjustable opening in a lens that controls how much light reaches the film, expressed as an f-number. Smaller f-numbers mean larger openings. Read the guide: Exposure: Aperture, Shutter and Stops

Aperture priority

A semi-automatic exposure mode in which you set the aperture and the camera chooses the shutter speed. Read the guide: Exposure: Aperture, Shutter and Stops

Archival processing

Fixing and washing film or prints thoroughly enough, often with a two-bath fixer and washing aid, that residual chemicals will not stain or fade them over decades. Read the guide: Storing Film and Negatives

ASA

The older American film speed standard. ASA numbers are the same as today's arithmetic ISO numbers, so ASA 400 film is ISO 400. Read the guide: Film Speed and ISO

B

Base

The clear flexible plastic, today usually polyester or cellulose triacetate, that carries the light-sensitive emulsion. Read the guide: How Film Works

Base fog

Density in unexposed areas of a developed negative, caused by the film base and by developing crystals that never saw light. It rises as film ages, which is why expired film often looks flat. Read the guide: Shooting Expired Film

Bellows factor

The exposure increase needed when a lens is focused much closer than infinity, because the light spreads over a longer distance. Calculated as (bellows extension ÷ focal length) squared. Read the guide: Large Format Movements

Blix

A combined bleach and fixer used in many home C-41 kits. It turns developed silver back into halide and removes it, leaving only the dye image. Read the guide: C-41 Color Developing at Home

Box speed

The ISO rating printed on the film box, which is what the manufacturer's development times assume. Read the guide: Film Speed and ISO

Bracketing

Making extra exposures above and below the metered setting, typically one stop each way, to make sure one frame is right. Read the guide: Exposure Latitude

Bromide drag

Streaks of uneven density running from the sprocket holes or from dense areas of the negative, caused by exhausted developer byproducts sliding down the film when agitation is too sparse. Read the guide: Stand Development

Bulb

The B shutter setting, which holds the shutter open for as long as the release is pressed. Used for exposures longer than the slowest timed speed. Read the guide: Reciprocity Failure

Burning

Giving part of a print extra exposure under the enlarger to make it darker, usually through a hole in a card. Read the guide: Dodging and Burning

C

C-41

The standard process for color negative film, run at 100°F (37.8°C). Almost every color negative film sold today is C-41. Read the guide: C-41 Color Developing at Home

Caffenol

A home-made black and white developer based on instant coffee, washing soda and vitamin C. Read the guide: Black and White Developers

Changing bag

A light-tight fabric bag with elastic armholes, used to load film onto developing reels or into sheet film holders without a darkroom. Read the guide: Developing Black and White Film at Home

Characteristic curve

A graph of a film's density against the log of exposure, showing its toe, straight-line section and shoulder. It explains how the film handles shadows, midtones and highlights. Read the guide: Exposure Latitude

Chromogenic black and white film

Black and white film that forms a dye image rather than a silver one and is processed in C-41 chemistry, such as Ilford XP2 Super. Read the guide: Types of Film

CLA

Clean, lubricate and adjust: a routine overhaul of a film camera's shutter, film transport and light seals by a repair technician. Read the guide: Buying a Used Film Camera

Color negative film

Color film that produces an orange-masked negative with inverted colors, which is printed or scanned to a positive. Developed in C-41. Read the guide: Types of Film

Compensating development

Development in which the developer exhausts in dense highlight areas while continuing to work in the shadows, compressing contrast. Stand development is the extreme case. Read the guide: Stand Development

Contact print

A print made with the negative pressed directly against the paper, so the print is exactly the size of the negative. Read the guide: Darkroom Printing Basics

Contact sheet

A contact print of a whole roll of negatives on one sheet of paper, used to choose frames for enlarging. Read the guide: Darkroom Printing Basics

Contrast

The difference between the light and dark tones in a negative or print. In film it depends on the scene, the film, exposure and development time. Read the guide: The Zone System

Cross processing

Developing film in the chemistry meant for a different type: usually slide film in C-41, which gives saturated, shifted colors and high contrast. Read the guide: Types of Film

Cyanotype

A simple iron-based printing process, invented in 1842, that makes a cyan-blue image on paper coated with ferric ammonium citrate and potassium ferricyanide and exposed to UV light. Read the guide: Alternative Processes

D

Dark slide

The removable cover on a sheet film holder or medium format film back that keeps light off the film until you are ready to expose. Read the guide: How to Load Film

Daylight-balanced film

Color film balanced for sunlight, around 5500K. Under tungsten light it records warm orange unless filtered. Read the guide: Types of Film

Densitometer

An instrument that measures the density of a negative or print, used for testing film speed and development. Read the guide: The Zone System

Density

How much light a developed area of film blocks. Thin negatives have low density; dense negatives have high density. Read the guide: Common Film Problems

Depth of field

The range of distances in front of and behind the point of focus that appear acceptably sharp. It increases as you stop the lens down. Read the guide: Depth of Field and Hyperfocal Distance

Developer

The chemical solution that turns exposed silver halide crystals into metallic silver, making the latent image visible. Read the guide: Black and White Developers

Developing tank

A light-tight tank with reels that holds film during processing, so chemicals can be poured in and out with the lights on. Read the guide: Developing Black and White Film at Home

Diffusion enlarger

An enlarger that lights the negative through a diffusing chamber, giving softer prints that show less dust than a condenser enlarger. Read the guide: Setting Up a Home Darkroom

Dilution

How a concentrated chemical is mixed with water, written as a ratio such as 1:31, meaning one part concentrate to 31 parts water. Read the guide: Black and White Developers

Dodging

Holding back light from part of a print during the enlarger exposure to make that area lighter. Read the guide: Dodging and Burning

DX coding

The checkered pattern of conductive and insulated squares on a 35mm cassette that tells a compatible camera the film speed and roll length. Read the guide: Film Speed and ISO

E

E-6

The standard process for color reversal (slide) film, producing positive transparencies. Read the guide: E-6 Slide Film Processing

ECN-2

The process for motion picture color negative film, such as Kodak Vision3. The film carries a remjet backing that must be removed during processing. Read the guide: Types of Film

EI

Exposure index: the speed you actually rate a film at, which may differ from box speed. Rating 400 film at EI 1600 and developing to match is a push. Read the guide: Film Speed and ISO

Emulsion

The light-sensitive layer of film or paper: silver halide crystals suspended in gelatin. Read the guide: How Film Works

Enlarger

A projector, mounted on a column, that shines light through a negative onto photographic paper to make a print larger than the negative. Read the guide: Setting Up a Home Darkroom

Expired film

Film used after the date printed on the box. How it behaves depends far more on how it was stored than on its age. Read the guide: Shooting Expired Film

Exposure

The total amount of light that reaches the film, set by the aperture and shutter speed for a given film speed. Read the guide: Exposure: Aperture, Shutter and Stops

Exposure compensation

Deliberately giving more or less exposure than the meter suggests, for subjects that would fool it, such as snow or a dark backdrop. Read the guide: Light Metering for Film

Exposure latitude

How far a film can be over- or underexposed and still give a usable image. Color negative film has wide latitude; slide film has very little. Read the guide: Exposure Latitude

Exposure value

A single number for a combination of aperture and shutter speed that gives the same exposure. EV 15 is roughly bright sun at ISO 100. Read the guide: Exposure: Aperture, Shutter and Stops

F

f-number

The ratio of a lens's focal length to the diameter of its aperture. The standard sequence, f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, changes the light by one stop at each step. Read the guide: Exposure: Aperture, Shutter and Stops

Fiber-based paper

Photographic paper with an uncoated paper base. It takes longer to wash and dry than resin-coated paper but is preferred for archival and exhibition prints. Read the guide: Darkroom Printing Basics

Film back

An interchangeable magazine on a medium format camera that holds the film, so you can swap film types mid-roll. Read the guide: Types of Film Cameras

Film holder

A double-sided holder that takes two sheets of large format film, each protected by its own dark slide. Read the guide: How to Load Film

Film speed

A film's sensitivity to light, given as an ISO number. Each doubling of the number is one stop more sensitive. Read the guide: Film Speed and ISO

Filter factor

How much extra exposure a filter needs, as a multiplier. A factor of 2 means one extra stop; 4 means two stops; 8 means three. Read the guide: Filters for Black and White Film

Fixer

The solution, usually sodium or ammonium thiosulfate, that dissolves the remaining unexposed silver halide so the image is no longer light sensitive. Read the guide: Developing Black and White Film at Home

Focal plane shutter

A shutter made of curtains or blades just in front of the film, used in most SLRs and many rangefinders. Read the guide: Types of Film Cameras

Fogging

Unwanted density on film from stray light, heat, age, radiation or chemical contamination. Read the guide: Common Film Problems

Fungus

Mold that grows inside lenses stored in damp conditions, visible as branching threads. It can etch the coatings permanently. Read the guide: Buying a Used Film Camera

G

Grain

The visible texture in a film image, made by clumps of developed silver or dye clouds. Faster films have larger grain. Read the guide: Film Grain

Grain aliasing

A false, harsh grain pattern created when a scanner's sampling interacts with the film grain, rather than the grain itself. Read the guide: Film Grain

Ground glass

The frosted glass focusing screen at the back of a view camera, where the image is composed and focused upside down. Read the guide: Large Format Movements

H

Halation

A glow around bright highlights, caused by light passing through the emulsion and reflecting back off the base. Cinestill films show red halation because their anti-halation layer is removed. Read the guide: Types of Film

Half-frame

A 35mm format of 18x24mm, giving twice as many frames per roll, usually oriented vertically. Read the guide: Film Formats Explained

Hyperfocal distance

The focus distance that gives the maximum depth of field at a given aperture, with everything from half that distance to infinity acceptably sharp. Read the guide: Depth of Field and Hyperfocal Distance

I

Image circle

The circle of usable image a lens projects. On a view camera it must be larger than the film to allow movements. Read the guide: Large Format Movements

Incident meter

A light meter that measures the light falling on the subject, through a white dome, rather than light reflected from it. Read the guide: Light Metering for Film

Infrared film

Black and white film sensitive into the near-infrared, used with a deep red or visual-opaque filter to make foliage glow white and skies go black. Read the guide: Types of Film

Instant film

Self-developing film, such as Polaroid and Instax, that produces a finished print shortly after exposure. Read the guide: Film Formats Explained

ISO

The international film speed standard. The arithmetic number (100, 400) matches the old ASA scale. Read the guide: Film Speed and ISO

L

Large format

Cameras and film of 4x5 inches and larger, almost always sheet film in a view camera with movements. Read the guide: Film Formats Explained

Latent image

The invisible image formed in exposed silver halide crystals, which developer then makes visible. Read the guide: How Film Works

Leaf shutter

A shutter built into the lens, with blades that open from the center. Quiet, and it syncs with flash at every speed. Read the guide: Types of Film Cameras

Light leak

Light reaching the film through a gap, usually worn foam seals or a damaged back, showing as streaks or patches of fog. Read the guide: Common Film Problems

Light seals

Strips of foam or yarn around a camera back and mirror that keep stray light out. Old foam turns sticky and must be replaced. Read the guide: Buying a Used Film Camera

Lith printing

Printing on suitable paper in a heavily diluted lith developer, giving prints with warm, soft highlights and hard black shadows. Read the guide: Alternative Processes

M

Medium format

Roll film formats on 120 film, from 6x4.5 to 6x9cm and beyond, much larger than 35mm. Read the guide: Film Formats Explained

Middle gray

The midtone a reflected light meter aims to render, often described as 18% gray. Zone V in the Zone System. Read the guide: Light Metering for Film

Monobath

A single solution that both develops and fixes black and white film, such as Cinestill Df96. Read the guide: Black and White Developers

Multigrade

Ilford's name for variable contrast paper, widely used as a general term along with its filter grades 00 to 5. Read the guide: Variable Contrast Paper

N

N development

Normal development in the Zone System. N+1 is expanded development to raise contrast; N-1 is contracted development to lower it. Read the guide: The Zone System

Negative

Developed film in which light and dark are reversed, and in color film so are the colors. Read the guide: How Film Works

O

Orange mask

The orange tint in the base of color negative film that corrects for imperfect dyes. It must be removed when scanning or inverting. Read the guide: How to Scan Film

Orthochromatic film

Black and white film sensitive to blue and green light but not red, so reds render dark and it can be handled under a red safelight. Read the guide: Types of Film

P

Panchromatic film

Black and white film sensitive to all visible colors. Nearly all general-purpose black and white film is panchromatic and must be handled in total darkness. Read the guide: Types of Film

Parallax

The difference between what a viewfinder sees and what the lens records, in cameras like rangefinders and TLRs that view through a separate window or lens. It grows at close distances. Read the guide: Types of Film Cameras

Photo-Flo

Kodak's wetting agent, added to the final rinse so water sheets off the film and dries without spots. Read the guide: Developing Black and White Film at Home

Platinum print

A print made in platinum, palladium or both, using iron salts as the light-sensitive component. Prized for its long tonal scale and permanence. Read the guide: Alternative Processes

Point-and-shoot

A compact, usually autofocus and automatic film camera. Read the guide: Types of Film Cameras

Pre-wash

Soaking film in water before development to bring the tank to temperature. Optional for most black and white films. Read the guide: Developing Black and White Film at Home

Press camera

A folding large or medium format camera built to be handheld, such as the Graflex Speed Graphic. Read the guide: Types of Film Cameras

Pull processing

Rating film below box speed and giving it less development, to lower contrast or rescue overexposed film. Read the guide: Push and Pull Processing

Push processing

Rating film above box speed and giving it more development to compensate. Increases contrast and grain. Read the guide: Push and Pull Processing

R

Rangefinder

A camera that focuses by superimposing two images in the viewfinder, seen through a window separate from the lens. Read the guide: Types of Film Cameras

RC paper

Resin-coated paper: photographic paper sealed in plastic so it processes, washes and dries quickly. Read the guide: Darkroom Printing Basics

Reciprocity failure

The loss of film sensitivity at very long or very short exposures, so a metered long exposure needs extra time. Read the guide: Reciprocity Failure

Reel

The spiral, plastic or stainless steel, that film is wound onto to hold it in a developing tank. Read the guide: Developing Black and White Film at Home

Reflected light meter

A light meter that measures light reflected from the subject. Camera meters are reflected meters. Read the guide: Light Metering for Film

Remjet

A black carbon backing on motion picture film that must be removed before or during processing. Read the guide: Types of Film

Reticulation

A crazed, cracked texture in the emulsion caused by a sudden large temperature change during processing. Read the guide: Common Film Problems

Reversal film

Film that develops directly to a positive image. Color slide film is reversal film. Read the guide: Types of Film

Rodinal

One of the oldest developers still made, first sold in 1891, a liquid concentrate used at high dilutions. Gives high acutance and visible grain. Read the guide: Black and White Developers

S

Safelight

A darkroom light of a color photographic paper is not sensitive to, usually amber or red. Read the guide: Setting Up a Home Darkroom

Salt print

The earliest paper print process, made by coating paper with salt, then silver nitrate, and exposing in sunlight. Read the guide: Alternative Processes

Scheimpflug principle

The rule that when the planes of the film, lens and subject meet at a common line, the entire subject plane is in focus. The basis of view camera tilts. Read the guide: Large Format Movements

Sheet film

Film cut into individual sheets, such as 4x5 and 8x10, for large format cameras. Read the guide: Film Formats Explained

Shutter priority

A semi-automatic exposure mode in which you set the shutter speed and the camera chooses the aperture. Read the guide: Exposure: Aperture, Shutter and Stops

Shutter speed

How long the shutter stays open. Each standard step, 1/60, 1/125, 1/250, halves or doubles the exposure. Read the guide: Exposure: Aperture, Shutter and Stops

Silver gelatin print

The standard black and white darkroom print, with an image of silver in a gelatin emulsion. Read the guide: Darkroom Printing Basics

Silver halide

The light-sensitive silver salts, such as silver bromide, that make up the image-forming crystals in film and paper. Read the guide: How Film Works

Slide film

Color reversal film that develops to a positive transparency, processed in E-6. Also called transparency or chrome film. Read the guide: Types of Film

SLR

Single-lens reflex: a camera with a mirror that shows the image through the taking lens, swinging up out of the way at exposure. Read the guide: Types of Film Cameras

Split-grade printing

Exposing a print in two parts, one through the softest filter and one through the hardest, to control highlights and shadows separately on variable contrast paper. Read the guide: Variable Contrast Paper

Spot meter

A reflected light meter that reads a very narrow angle, often one degree, so you can measure individual tones in a scene. Read the guide: Light Metering for Film

Stabilizer

The final bath in color processing that improves dye stability and helps the film dry evenly. Read the guide: C-41 Color Developing at Home

Stand development

Developing film in highly dilute developer for a long time with little or no agitation, letting the developer exhaust in the highlights. Read the guide: Stand Development

Stop

A doubling or halving of exposure. Opening the aperture one stop, slowing the shutter one step or doubling the film speed each give one stop more exposure. Read the guide: Exposure: Aperture, Shutter and Stops

Stop bath

A weak acid bath, or plain water, used after the developer to halt development quickly and protect the fixer. Read the guide: Developing Black and White Film at Home

Sunny 16 rule

The rule that in bright sun the correct exposure is f/16 at a shutter speed of 1 over the film speed. Read the guide: The Sunny 16 Rule

Surge marks

Dense streaks next to sprocket holes, caused by developer surging through them during overly vigorous agitation. Read the guide: Common Film Problems

T

Test strip

A strip of photographic paper given a series of stepped exposures to find the right exposure time for a print. Read the guide: Darkroom Printing Basics

Thin negative

A negative with too little density, usually from underexposure or underdevelopment. Read the guide: Common Film Problems

Tilt and shift

View camera movements that angle the lens or film (tilt and swing) or move them parallel to each other (shift, rise and fall). Read the guide: Large Format Movements

TLR

Twin-lens reflex: a camera with two matched lenses, one for viewing through a waist-level finder and one for taking the picture. Read the guide: Types of Film Cameras

Toning

Treating a print in a chemical toner, such as selenium or sepia, to change its color and improve its permanence. Read the guide: Darkroom Printing Basics

Tungsten-balanced film

Color film balanced for incandescent light, around 3200K, such as Cinestill 800T. In daylight it records blue unless filtered. Read the guide: Types of Film

V

Van Dyke brown

An iron and silver printing process that gives a rich brown image, related to the cyanotype. Read the guide: Alternative Processes

Variable contrast paper

Black and white paper whose contrast changes with the color of the exposing light, controlled with filters from grade 00 to 5. Read the guide: Variable Contrast Paper

View camera

A large format camera with a lens and film standard joined by bellows, allowing movements, and focused on a ground glass. Read the guide: Types of Film Cameras

W

Wet plate collodion

A 19th-century process in which a glass or metal plate is coated with collodion, sensitized and exposed while still wet, then developed immediately. Read the guide: Alternative Processes

Wetting agent

A surfactant added to the final rinse to help water drain from film without leaving drying marks. Read the guide: Developing Black and White Film at Home

Z

Zone focusing

Presetting focus to a distance and relying on depth of field, rather than focusing each shot, common in street photography. Read the guide: Depth of Field and Hyperfocal Distance

Zone System

A method of exposure and development control, devised by Ansel Adams and Fred Archer, that divides tones into eleven zones from pure black (0) to pure white (X). Read the guide: The Zone System

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