Film Terminology

Refers to Medium Format film, which comes in two standard lengths, 120 and 220, with 120 being the most common. The 220 size is simply twice as long as 120. Larger than 135 film, it is 61mm wide and does not have perforated edges (the film moves from one spool to another in-camera when shooting - no need to rewind after finishing a roll). 120 film generates anywhere from 10 - 16 exposures per roll, depending on the camera used. Typical sizes/ratios are 6x7cm (10 exposures), 6x6cm (12 exposures), and 6x4.5cm (16 exposures). 220 film does not have a protective backing paper on it (allowing the longer film to fit in the same spool as 120 film).

The most common name is "35mm" and it will produce between 24 to 36 exposures, depending on the packaged length. It has a standard frame size of 36x24mm. The film has perforated edges, which allow the film to be wound to and from a spool within the camera back.

Aperture is the diameter of the opening in your lens that light passes through to the film in your camera. It is measured as a fraction that relates to the opening of the lens, and is referred to as an f-stop, where f-stop = focal length of the lens/diameter of the lens. The wider your aperture, the lower the f/number. A lower f-stop means more light will be let in through the lens, because the opening is wider. A narrower opening will allow for less light to pass through, and is communicated as a higher f-stop.

Universal f-stops:

Aperture also affects depth of field. The smaller the aperture (larger the f-stop), the greater your depth of field (how deep within a scene will be in focus in your image).

A ring around a lens used to manually adjust the aperture size. May modern lenses don’t have an aperture ring; instead, the aperture setting can be adjusted electronically via controls on the camera body.

The out-of-focus blur effect seen in the foreground or background of a scene. Bokeh characteristics are affected by the shape of the lens’ diaphragm and the aperture setting used to create a photograph.

The name often used for the hemispherical plastic dome on a light meter, also known as a lumisphere. Used to measure light.

The development process intended for color negative films. During the "development" step of C-41 film processing, an oxidized developer reacts to the color layers of the film emulsion to result in the formation of dyes while the silver halides are concurrently being transformed to silver metal. When executed by a commercial C-41 processor, there is an additional step in the C-41 process after the initial development, through which a bleach solution is used to convert the developed silver image into silver halides, so that it is soluble in the fixer solution. There are simplified versions of the process that use a combined bleach-fix step. However, this is not used by professional labs, and is marketed for home use only.

Density is the measurement of opacity within a film negative or transparency. A film’s density is affected by exposure and development. The more a film is exposed to light, and the more intense that light is, the denser the film negative or transparency once developed. The density within a film negative can vary within the scene captured, based on the lightness or darkness of each component of the frame.

Depth of field is the distance in front of and behind the plane of focus (the point within a scene that appears sharp) that also appears acceptably sharp. With a large depth of field, a greater amount of the frame surrounding the plane of focus will appear sharp. A shallow depth of field will make for a faster drop-off of focus, creating a blurry background and foreground (often a sought after look for portraits). Depth of field is determined by a combination of factors including aperture, lens focal length, and film format.

Also known as processing. The chemical process used to yield a visible image on exposed film. When photographic film is exposed, a "latent image" (an invisible image) is formed on the film through the molecular chemical reaction of the film emulsion when exposed to light. In order to make this latent image visible, the film is processed by being submerged in a series of chemical baths. When processed, the exposed photographic film darkens or lightens to form a visible image. Once the film has been processed, the film exposure is permanent, and is now insensitive to light. There are three main types of film processing used today: C-41, E-6, and Black & White.

When a single frame of film is exposed twice, creating a layered effect with the two exposures.

Small artifacts that catch on the surface of a film negative or transparency that are visible when printing or scanning. While maintaining dust-free film is something to strive for, it is not always possible (dust particles in the air sometimes can’t be avoided). Many modern film scanners can remove visible dust from the final digital file through the combined use of infrared light and scanning software.

Dynamic range is the measurement from darkest shadows (complete black) to brightest highlights (complete white) that a film can capture at the same time. A film with a higher dynamic range can capture an image with a larger difference between the darkest and lightest variables within the scene. A film with a lower dynamic range would not be able to capture the same scene correctly, washing out highlights and losing detail in the shadows.

E-6 processing is used for the development of transparency films. During the E-6 development process, a reversal bath is included, which turns the negative silver halides within each layer into a positive image.

The light-sensitive chemical layers of photographic film. These layers are made up of a gelatin mixture containing microscopically small, light-sensitive silver halide crystals. The sizes and varying characteristics of the crystals determine a film’s sensitivity, contrast and resolution. When exposed to light, these crystals chemically change (with the change being proportional to the amount of light they are exposed to), which is what creates the imprinted image in the emulsion that is visible once the film is developed.

Exposure is the total amount of light that reaches the film, determined by the length of time the light hits the film and the intensity of the light.

Exposure latitude is the span of under or overexposure a film can tolerate and still produce a negative or transparency with an acceptable level of quality. Certain films have more latitude than others. For example, color negative film has more exposure latitude than slide film.

Often referred to as EI, exposure index is the film speed value that is assigned to film. It is subjective, and does not have to match the film’s speed/ISO. For example, if a photographer prefers slightly overexposed results when shooting FUJICOLOR PRO 400H, he or she may rate the film at 200 and set the ISO at 200 on the meter before taking a reading, thus setting the film’s EI to 200.

The amount of time that film is exposed to light, as determined by your shutter speed.

The "Exposure Triangle" is a way of demonstrating how aperture, shutter speed and ISO correlate and work together to achieve your desired results when exposing an image.

Film speed is defined by a film’s sensitivity to light, and is most commonly referred to as ISO. The lower the ISO number, the less sensitive to light, and the higher the number, the more sensitive to light. The term film "speed" derives from how quickly a film emulsion can be properly exposed. For example, film with ISO 1600 is a fast film because it is highly sensitive to light and requires a short exposure time/less light in order to create proper density. ISO 50 film is a slow film because it is less sensitive to light and requires more exposure to light in order to produce the same image density. The ISO speed of a film is a fixed value and cannot be changed in the camera as is the case with feature changes applicable to a digital camera.

A visibly apparent lack in image quality, most commonly visible on negative film as low contrast with a “fog” cast over the entire image, caused by a deterioration of the photographic film. Fogging can be caused by a number of external factors including x-ray damage, heat, moisture, deterioration of the film’s chemical emulsion layers over time, accidental exposure to light, or incorrect chemical development.

Another name for aperture (see above), but specifically refers to the actual numbers marked on a lens.

Universal f-stops:

Film "grain" is the visible appearance of the silver halide particles within the exposed emulsion of processed film. The amount of grain and size of grain are both optical effects that depend on the film stock and distance of observation (how much the image is magnified when printing or viewing on a monitor).

The size of silver halide grains varies in film stocks. Larger grains of silver halide give film a greater sensitivity to light, and are used in higher-speed films (such as ISO 400 and above). Fine-grain films are generally slower speed, meaning they are less sensitive to light and require more exposure time or brighter light than faster-speed films that produce more visible grain in images.

ISO stands for International Standards Organization, and is an industry standardized scale for measuring sensitivity to light. See Film Speed above. The lower the ISO number, the less sensitive to light, and the higher the number, the more sensitive to light.

A series of curved glass or plastic pieces in a tube that attaches to the front of your camera body, through which the image you are capturing is focused before being imprinted on your film.

When there is a hole or gap in the body of a film camera, it allows light to "leak" through the intended light-proof chamber, exposing the film to diffused light that is separate from the controlled light exposure that takes place when the shutter is released.

A tool used to measure the amount and intensity of light falling onto or being reflected by a subject. The meter reading is then used to calculate the correct shutter speed and/or lens aperture for best exposure results.

A method for estimated proper exposure to properly capture the moon based on the lunar phases. For a full moon, set your aperture to f/11 and shutter speed to the ISO film speed or closest equivalent rounding up (for example, if shooting ISO 100 film, your shutter speed will be 1/125). For a half moon, set your aperture to f/8, for a quarter moon, f/5.6, a crescent moon, f/4, and for a total eclipse, f/2.8.

Often referred to as a "bulb," it is the hemispherical plastic dome on a light meter used to measure light.

A film negative is the image created on a strip or sheet of photographic print film after it is exposed to light and developed. It is called a negative because it is the reverse of the actual image. The lightest areas of the image appear darkest and the darkest areas appear lightest. This reversal is caused by the light-sensitive chemical emulsion darkening as part of the chemical reaction that occurs when exposed to light. So, the more light, the stronger the chemical reaction and the darker the emulsion will become. With color negatives, the colors are also reversed in the negative (i.e. a red rose will appear cyan and a blue sky will appear yellow in the negative).

When film is exposed to more light than is needed to create a properly exposed image. Overexposure results in a denser negative and excess shadow detail and compressed highlights. Extreme overexposure can lead to color shifts, especially in the highlights, and flat, low-contrast results.

Also known as development (see above).

Film that is wound on a spool without an external cartridge covering it. 120 and 220 Medium Format films are roll film.

Also known as large format film, sheet film is any film with a single frame size of 4x5 inches or larger. Each frame is a separate sheet, not on a consecutive roll or spool like 135 and Medium Format films.

The length of time your shutter is open when you press the shutter release button on your camera. The longer your shutter is open, the more your film is exposed to light. Shutter speed is measured by fractions of a second. For example, if your shutter speed is 1/30, the shutter will be open (and your film exposed to light) for one thirtieth of a second. Generally, shutter speeds increase in a (sometimes rounded) 1:2 ratio, moving from 1/4 to 1/8, 1/15, 1/30, 1/60, 125, 1/250, and so on.

A light-sensitive chemical compound used in photographic film emulsion. When exposed to light, the silver halide crystals within film emulsion chemically change (with the change being proportional to the amount of light they are exposed to). This change is what creates the imprinted image (often called "exposure") in the emulsion on the strip of film. This exposure can then be seen once the film is developed.

Another name for reversal film. Reversal film produces a positive transparency when exposed and developed. It is also referred to as "Chrome film."

The holes along each side of 135 (35mm) film creating perforated edges. The sprocket holes allow for the film to catch on the sprockets within the camera back used for advancing and rewinding the film.

A method for estimating proper exposure in various daylight lighting conditions. The formula begins with the premise that on a bright, sunny day while shooting in direct sunlight, you set your aperture to f/16 and shutter speed to the ISO film speed or closest equivalent rounding up (for example, if shooting ISO 100 film, your shutter speed will be 1/125). From this base setting you can adjust your f-stop down as needed for different lighting scenarios. For example, in partially cloudy light, you’d move down to f/11, in overcast light, f/8, and in extremely overcast light, f/5.6.

When using color reversal film, the exposed film is not called a negative. It is called a transparency. It is a positive transparency, or diapositive, because the exposed film is not a reversal of the image. Instead, the exposure on the film is a true representation of what was photographed.

When film is not exposed to sufficient light to create a properly exposed image, it is underexposed. Underexposure results in a lack of density in the negative (referred to as a "thin" negative), with little to no detail in the shadows and a final image without much contrast between shadows and highlights.

A technique for calculating correct overall exposure based on individual readings of specific elements within a scene. The system rates brightness from 0 to 10, with black being 0, middle gray 5, and pure white 10. The values are referred to as zones.