Collectible Cameras :: Glossary


Kindly reproduced with the permission of Amherst Media, Inc.  McBrooms Camera Bluebook

Action Finder:

An accessory viewfinder with a large eyepiece for interchangeable-finder camera

systems that allows an eye-relief of up to several inches, while still allowing total visibility of the viewing area. Popular for sports photography and other situations in which the photographer

may need to observe action outside the viewfinder frame.


AE: Auto Exposure.

A system in which the camera determines a scene’s exposure based on lighting conditions and selects the correct aperture for a user-selected shutter speed, or the correct shutter speed for a user-selected aperture, or, with Program AE, both.


AE Lock: Auto Exposure Lock.

Usually a button that locks in the selected AE setting. Most useful for holding an AE reading when recomposing a scene in unusual lighting situations.


AF: Auto Focus.

Angle Finder: An viewfinder accessory that attaches to the eyepiece of a camera, which projects the image at a 90 degree angle. Useful for copy work and other instances in which straight-on viewing may be awkward.



The interior opening of a lens. Usually the aperture size can be varied by an iris diaphragm mechanism to control the amount of light reaching the film plane. Some lenses have fixed apertures; that is, they cannot be varied in size. Aperture Numbers:

See F/stop.


Aperture-Priority AE:

An auto exposure mode in which the camera determines the shutter speed based on a scene’s light conditions and the lens aperture the user has selected.


Auto Bracketing:

A feature on many modern cameras that will automatically vary exposure for a series of frames, usually in 1/2 stop increments. This slight variation in exposure between successive shots is called bracketing and is often used to insure that at least one frame in a series is properly exposed.


Auto Diaphragm:

A lens diaphragm that is coupled by means of a mechanical or electronic link to a camera body such that it will close down to a pre-selected opening size just prior to and during exposure. 

Auto Film Loading:

A system on many modern cameras in which the camera secures the film to the film take-up spool and automatically winds the film to the first frame.


Auto Film Rewind:

A system in which the camera will rewind the film automatically once the last frame has been exposed.



American Standards Association. Former standard used to determine film speed and, for all practical purposes, synonymous with the current designation, ISO. See ISO, Film Speed.

Auto Winder:

Also called a winder, an auto winder is a film winding accessory that is usually attached to the bottom of a camera. Typical settings on a winder are S for Single frame and C for Continuous. A winder will usually advance film at rates up to 2 frames per second when on the continuous setting. Not all winders have

a Continuous setting. Not all cameras will accept winders.


Averaging Meter:

An exposure meter which reads and averages all light values within its range of acceptance, and which recommends exposure based on the lighting situation.


B: Bulb.

A manual setting on a camera in which the shutter will remain open for as long as the shutter release is depressed.


BLC: Back Light Control.

Usually a button on auto exposure cameras that, when depressed, will overexpose the frame by 1 1/2 to 2 stops. Used in situations where the subject is close to a bright light source, such as a window. Often this sort of lighting situation will fool a camera’s meter and cause the subject to be underexposed.


Bottom-Centerweighted Metering:

Centerweighted metering that has a stronger emphasis toward the bottom of the image area. The idea behind this is to reduce the influence a bright sky may have on outdoor subjects.


CdS: Cadmium Sulfide.

The first substance used in metering cells for battery-powered light meters. It offers better low-light sensitivity and more accurate response to light temperature than Selenium meters.


Continuous AF:

An autofocus selection in which a camera will autofocus continually on a subject, especially a moving one, and will allow exposures to be taken whether or not the subject is in focus. Also called Servo AF.


Data Back:

An accessory camera back that will imprint data on the film emulsion, usually within the frame. A typical databack will imprint the current date, but little else. Databacks with advanced features, usually available only for cameras with advanced features, may offer such additional options as printing information

between frames, printing exposure information, an intervalometer and filmrewind options.


Depth-of-Field Preview:

A feature on many cameras, usually a button or a lever, that allows the user to examine the actual depth of focus at a given aperture. The smaller the aperture (the larger the aperture number), the greater the depth of focus.


DX Film Coding:

On cameras supporting it, a feature that will automatically set a film’s ISO (ASA) speed based on coded information on the film cassette. Some cameras allow users to override this feature and select their own ISO settings.


EI: Exposure Index.

A user-assigned film speed that differs from that recommended by the film manufacturer.


EV: Exposure Value .

EV is a light measurement method in which a given exposure ratio between apertures and shutter speeds is assigned a number independent of film speed. For example: 1/60 @ f/8 = 1/125 @ f/5.6 = 1/250 @ f/4 and so on. These settings represent equivalent exposure values and have the same EV number. In the above

example, that number is EV 12 and will always be EV 12, no matter what the film speed is. Each successively higher whole number on the EV scale represents a doubling of the amount of light or exposure a subject receives, just as each successively lower number represents a decrease in exposure by one-half.

When metering a scene at different ISO settings, however, the EV number will change. A scene metered at EV 12 at ISO 100 will need an exposure of 1/60 @ f/8 (or its equivalent). This same scene, when metered at ISO 400, will have an EV of 14, requiring an exposure of 1/60 @ f/16 (or equivalent). The difference of 2 steps on the EV scale corresponds to a 2x2, or a four-fold increase in light or light sensitivity, which is

exactly the difference between that of ISO 100 and ISO 400. If it sounds confusing, just think about it for a minute. It makes sense. The handy thing about the EV system, once one gets the hang of it, is that one can think in simplified terms when calculating exposure.


Exposure Compensation:

A feature on most auto-exposure cameras that allows the user to bias exposure, typically in 1/3 or 1/2 stop increments, usually over a 2-stop range. Useful for unusual lighting situations that may otherwise fool a camera’s meter.


Extension Tube:

Often available as a set with three to four different lengths. An extension tube placed between lens and camera, will reduce the minimum focusing distance, while increasing the magnification. Auto extension tubes retain the coupling mechanism between lens and camera, allowing auto diaphragm operation.


Film Speed:

The “speed” of a film’s emulsion is determined by its relative sensitivity to light. A “fast” film is one that is sensitive to small amounts of light, enabling shorter exposure times in low-light situations. A “slow” film, on the other hand, is better able to handle extremely bright situations. The trade-offs are: a fast film’s

inherent grainy structure will reduce a photograph’s sharpness whereas a slow film has a much smaller grain size, hence much better sharpness; a slow film is inconvenient to use in low or subdued-light situations because of the longer exposure times involved.


Fish Eye:

A very short focal length lens (typically in the range from 6mm to 8mm for 35mm cameras) with a 180° or more field view. Fish eye lenses cause extreme distortion of perspective and make a circular image. Straight lines that pass through the center of the image area remain straight; all others become progressively more distorted as they are located closer.


Flash Sync:

The fastest shutter speed setting at which a flash can be used. See M sync and X sync.



Frames Per Second.



Theoretically, the mathematical ratio of a lens’ focal length to the diameter of its front element. For example, (100mm focal length)÷ (50mm front element diameter) = 2, so this lens would be considered a 100mm f/2. The larger the maximum aperture, the lower the f/ratio and the more light an optic gathers. Lenses with low f/ratios are frequently referred to as “fast” lenses because they allow faster shutter speeds than lenses

with smaller maximum apertures.



A ratio of a lens’ focal length to the size of the opening of its interior diaphragm. With adjustable diaphragms, this ratio can change and is expressed as a logarithmic scale on the lens’ aperture ring. The higher the number, the smaller the opening. See F/ratio.


Focus Priority AF:

An autofocus feature in which the camera will not allow an exposure to be made until the subject is in focus.


Focusing Screen:

The ground glass or fresnel panel, made from either glass or plastic, on which the image actually appears for viewing. Some 35mm and medium format cameras have interchangeable focusing screens, which provide the user with a greater variety of composition or viewing options.


Full-Frame Fish Eye:

An apparent contradiction in terms, a full-frame fish eye lens has a focal length typically in the range of 15mm to 16mm for 35mm cameras. The image is distorted as is the case with a fish eye lens, but the image is not circular, hence the designation “full-frame.” A full-frame fish eye lens has a 180° field of view measured on the diagonal.


GN or Guide Number:

A measurement of a strobe’s light output that can be used to determine exposure according to the following formula: (Camera to Subject Distance) x (Lens Aperture) = Guide Number. In the U.S., the Distance to Subject is expressed in feet (elsewhere, it’s expressed in meters) and the Lens Aperture is expressed in

f/stops. The guide number of a strobe is always given in terms of feet or meters at a particular ISO number. When a guide number is cited in this book, it is given in feet at ISO 100.


ISO: International Standards Organization.

In photography, the letters ISO are most often associated with film emulsion speeds. To the casual observer ISO may seem synonymous with the older filmspeed rating, ASA (and it is treated the same in this book), but that isn’t quite the case. When used as a film-speed rating, ISO incorporates both the ASA rating

used in the U.S. and the DIN rating used in Europe. Using the former standards, a film emulsion rated at ASA 100, for example, carried the equivalent DIN rating of 21°. The ISO rating of this same film emulsion is now expressed as 100/21°.



In photography, a term denoting higher than normal magnification and usually expressed as a ratio. For example, a macro ratio of 1:2 means that the image size on the film is 1/2 its actual size. Generally, “true” macro magnification is considered to begin at a ratio of 1:2. Macro is also a setting found on many zoom lenses that allows a degree of close focus. Most zoom lenses with a macro setting do not offer true macro focusing, in that they cannot focus down to a minimum of a 1:2 ratio.


Macro Lens:

Also called a Micro lens. Macro lenses are specially designed, flat-field optics with close-focusing capabilities and maximum macro ratios of usually either 1:2 or 1:1 (1/2 or full life size at the filmplane), depending upon make and model. Macro lenses (except some bellows lenses) retain infinity focus and work well for regular photography. Some macro lenses are designed especially for use with bellows and cannot be focused without them.


Macrophoto Lens:

A special, high-magnification lens that must be used in conjunction with a bellows. Image magnifications from 2x to 20x life size are possible with sufficient extension.


Manual Diaphragm:

A variable, iris-bladed mechanism inside a lens that is coupled to an aperture ring, but has no coupling linkage to the camera. When using a lens with a manual diaphragm on cameras with TTL meters, metering must be done at the lens’ taking aperture using either stop-down metering or aperture priority AE.


Manual Exposure Mode:

An exposure method in which the user selects both the aperture and shutter speed according to either the camera’s built-in meter or an external source.


Micro Lens:

See Macro Lens.


Mid-Roll Rewind:

A feature on many modern SLRs with built-in motordrives that allows the user to rewind a roll of film before it is totally exposed. This is a useful feature when the photographer wishes to change film emulsion types before the existing roll is finished. Most cameras that offer this feature wind the film back into the cassette,

leaving no film leader protruding. Some cameras allow the user to select an option which stops rewinding just short of sucking the leader back into the cassette, which makes it much easier to reload the roll at a later time.


Mirror Lock-Up:

A feature on many professional-oriented SLRs in which the camera’s mirror can be raised and locked manually. Its main purpose is to minimize mirror-induced vibration when taking high magnification

photos, or when using slow shutter speeds, or both. Most 35mm SLRs that have vertical focal-plane shutters offer a pseudo mirror lock-up capability, which can be employed by using the self-timer. After charging the self-timer mechanism (or selecting the self-timer option on an electronic SLR), when the shutter is released the mirror raises immediately. In most cases the ensuing delay is sufficient to eliminate fuzzy photos caused by mirror- induced vibration.


Motor Drive:

A high-speed film winding accessory that attaches to the base of a camera and that typically offers continuous film winding speeds which may range anywhere from 3 frames per second to over 6 frames per

second (depending on the model, the camera, and the shutter speeds selected). Most motor drives offer a single-frame setting and many offer two or more continuous speeds. Some motor drives have motorized rewind.


M sync:

The flash sync setting or switch for M-class flashbulbs.


Multiple Exposure Capability:

The ability to take more than one exposure on a single frame. Many cameras that offer this feature have a separate switch for this. Others require that the film-rewind button on the bottom of the camera be depressed prior to each additional exposure. Still other cameras don’t support this feature at all.


OTF: Off The Film plane.

This refers to a method of either TTL exposure metering or TTL flash metering in which the reflectance of the film is used to calculate correct exposure. See TTL.


Partial Metering: Also called

Selective Metering. A metering system in which only a specified central area within the viewfinder meters a scene. This system is more useful in critical exposure situations than the various averaging methods, since extraneous light in a scene will not affect a camera’s meter as long as it remains outsidethe metering area.


PC Lens:

A Perspective Control,or Shift lens. Allows the front element of the lens to be shifted away from the centerline. Most common in focal lengths ranging from 24mm to 35mm. A PC lens is used mostly for architectural photography and other situations in which converging lines are undesirable.


PC Socket:
Push Connector Socket. A receptacle for standard flash cords, enabling a flash to be used off the camera.



A solid, five sided, aluminized prism used to reflect the image from a camera’s focusing screen to the eyepiece.



Marketing jargon for plastic. To be fair, though, polycarbonate is a general term which includes a variety of plastics, all of which are noted for durability and a high melting temperature. When reinforced with carbon fibers or fiberglass, the resulting composite’s strength and durability rivals and, in some cases, surpasses

that of many metals.



A series of mirrors used to reflect an image from the focusing screen to the eyepiece.


Predictive Focus:

A feature on some of the latest-generation autofocus cameras that, when engaged, will track a moving subject and predict its location and correct focus at the instant of exposure.



This term applies to certain manual-diaphragm lenses that have an additional ring adjacent to the aperture

ring. When rotated one way, this additional ring will open the aperture to its maximum, facilitating ease of focus. The ring is then rotated in the opposite direction to close the iris down to the preselected taking aperture.



An auto exposure mode in which the camera selects both the aperture and shutter speed according to a scene’s lighting conditions.


Program Shift:

An adjustment to the program setting that allows the user to bias toward higher or lower shutter speeds, or greater or smaller apertures, while maintaining the inversely proportional relationship between the two values. Rangefinder: A term used to indicate a camera design, but which is more precisely a component

of a camera design. An optical rangefinder is a system of prisms or mirrors or both that use a parallax method of measurement to determine distance and correct focus. Focus is obtained by bringing a double image visible in the center of the viewfinder frame into coincidence. A big advantage to a rangefinder camera is the lenses it can use. Lenses for rangefinder cameras often exhibit superior sharpness and contrast because of their less complex design. (A general rule in optics is that the more elements a lens has, the greater the image degradation it will experience.) Another plus is that because a rangefinder camera does not have a reflex mirror it is much quieter than an SLR and produces much less vibration. Its disadvantages include an inability to see exactly that which the lens sees (although most rangefinders have parallax correction) and a limited lens selection, especially in focal lengths greater than 135 millimeters.


SBC: Silicon Blue Cell.

A recent-technology metering cell that offers improved sensitivity over silicon photo cells.


SCA: Sync Cord Adapter.

A system of compatibility for flash photography that has become the standard in Europe and is slowly gaining in popularity elsewhere.


Selective Metering:

See Partial Metering.

Servo AF:

See Continuous AF.


See Program Shift.

Shift Lens:

See PC Lens.

Shutter-Priority AE:

An auto exposure mode in which the camera determines the lens aperture based on the scene’s light conditions and the shutter speed selected by the user.


Shutter Speed:

The time that a shutter remains open. Typically expressed in whole numbers on a shutter speed dial or display, the numbers above 1 are actually reciprocals (i.e. 250 is actually 1/250 second). The numbers below 1 on certain electronic SLRs are multiples of seconds (i.e. 8 = 8 seconds).


Single Shot AF:

Usually coupled with a camera’s focus priority feature, this system allows only one exposure at a time, and then only after the subject is in focus.


SLR: Single Lens Reflex.

The design of most interchangeable-lens 35mm and medium format cameras. Most SLRs have a mirror located directly behind the lens, which projects the image onto a focusing screen, then through a pentaprism (or in some cases a porroprism), which provides the user with a right-side-up, left-to-right corrected

image. In a typical SLR the mirror swings up immediately before exposure, allowing the image to be projected directly onto the film plane. Advantages to the SLR design include: most SLRs have TTL metering and many have TTL flash metering; what you see is what you get because you’re observing the scene

through the lens; a wide range of accessories and lenses. Disadvantages include:the user cannot see the image at the moment of exposure because the mirror rises, momentarily blanking out the scene visible from within the viewfinder (Exceptions to this include a handful of SLR’s that have fixed, pellicle mirrors. Their main disadvantage, however, is an inherently dimmer viewfinder.); a higher noise and vibration level due to the mirror assembly’s operation.


SPD: Silicon Photo Diode .

A widely-used type of metering cell that has all but replaced its CdS predecessors. Its advantages over CdS is a faster response, increased light sensitivity range, and no “memory,” an affliction of CdS meters in which the meter will “remember” a bright scene for a while after being exposed to it.
Sport Finder:

See Action Finder.


Spot Meter:

A light meter that is either hand-held or, in some cameras, built in to the camera. A true spot meter features a 1° angle of acceptance, thereby allowing the photographer to make critical exposure measurements of a scene. A built-in spot meter meters the central area of the viewfinder only, typically from 1% to 3% of the viewfinder image.



Sometimes synonymous to f/stop, “stop” also means a single gradation of exposure value (see EV). When a photographer says, for example, that a scene has a three-stop range between highlight and shadow, he or she is referring to a three step range in exposure values, or to put it another way, that the highlight area is receiving eight times the light that the shadow area is.


Stop-Down Metering:

A metering method that measures exposure at a lens’ taking aperture. Used nowadays primarily with lenses that have manual or fixed apertures. Many early SLRs with TTL meters use this method for determining exposure. Modern full-featured SLRs retain this capability. Strobe: Electronic Flash.


T: Time.

When making an exposure with a camera set on “T,” the shutter will remain open until the T setting is disengaged. Seen now mostly on older cameras, the T setting is essentially “B” with a built-in lock.



This device fits between the lens and the camera. It is an economical method of increasing a lens’ focal length without affecting its minimum focusing distance. The most popular configuration is the 2x teleconverter, which doubles a lens’ focal length. Other magnifications are, however, available: most common being 1.4x and 3x. But you never get something for nothing. The increase in power also corresponds to the amount of light lost when using one; e.g. a 2X increase in focal length results in a two-stop loss of light. However, if your camera has a TTL meter, it will automatically take into account this light loss and display the resulting correct exposure.


TLR: Twin Lens Reflex.

A camera with separate taking and viewing lenses. A mirror is used in conjunction with the viewing lens to reflect the image onto a focusing screen. The image is right-side-up, but uncorrected from right to left (i.e. backwards).


Trap Focus:

A feature on some latest-generation autofocus cameras in which the camera will automatically take a photograph once a subject enters a pre-determined area of focus.


TTL: Through The Lens.

This acronym is often used when referring to viewing an image, a meter design, or a flash metering method. All have the same thing in common in that they refer to the ability to evaluate a scene as the lens sees it, or Through The Lens.


Variable Aperture:

A design common to modern zoom lenses in which the aperture setting changes as the focal length is changed. Usually as much as one stop of light is lost when zooming from the shortest focal length to the longest. This presents little problem when using a camera in an auto exposure mode, but can be annoying

when using it in manual or when using it with a manual strobe, especially at intermediate focal lengths.



Varifocal Lens:

Often mis-categorized as a zoom lens, a varifocal “zoom” requires refocusing after a shift in focal length, except at infinity focus. Advantages to the varifocal design include fewer lens elements than a true zoom of the same focal length, and a more compact size.


Waist Level Finder:

A collapsible hood, which, when opened, gives the photographer a direct view of the camera’s focusing screen. Called a waist level finder due to the fact that the focusing screen is corrected for best viewing from that distance. Often, a waist level finder will have a magnifier incorporated into its design, which can

be moved into position above the focusing screen, and which enables the photographer to examine a magnified image for critical focus. The view through a waist level finder is not corrected from right to left (i.e., images seen are backwards).



See Auto Winder.


X sync:

The fastest shutter speed setting at which an electronic flash can be used. Often symbolized by a lightning bolt.


Zoom Lens:

Available in two basic designs, known as either two-ring or one-touch, zoom lenses provide photographers with continuously variable focal lengths throughout their range. Many two-ring, or twotouch, zooms are older vintage lenses, whereas most newer zooms are of the one-touch style. Exceptions to this are autofocus zooms, which are two-touch. Each style has its advantages and disadvantages: The two-ring style allows zooming without accidentally shifting focus, but because it has separate rings for focus and zoom control, it is a little slower to use (not a problem with autofocus cameras, however). The one-touch style is quicker to use, since the single collar allows simultaneous focusing and zooming, but the focus can be shifted inadvertently when zooming from one focal length to another.
Kindly reproduced with the permission of Amherst Media, Inc.  McBrooms Camera Bluebook.