Aperture: The aperture is the physical lens opening on your camera. It is adjusted to open and close in f-stop increments, allowing more or less light in with a larger or smaller opening. The iris diaphragm inside the lens of your camera is adjusted to alter the quantity of light that will reach your film. Each aperture opening, or f-stop, lets in twice as much light as the smaller f-stop before it, and half as much light as the larger f-stop after it. For example, f5.6 will let in twice as much light as f8, and half as much light as f4.



   Automatic Mode/Automatic Exposure: The automatic mode is a setting on your camera that allows the camera to use its internal meter to automatically adjust the aperture and shutter speed for a shot based on the prescribed ISO speed of your film, and the available light. When using studio flash units, you can not leave your camera in automatic mode, as its internal meter will not be able to detect the light that will be emitted by your flash units, and will thus be set to an inaccurate shutter speed and aperture opening, causing your picture to be overexposed. Furthermore, when in automatic mode, many cameras have TTL metering which will send out an infrared signal to read the light, and that signal may inadvertently trip your unit’s built-in slave tripper.

Ambient Light/Available Light: Ambient or available light refers to the light that already is present in the location where you plan to shoot. This light could be sunlight or indoor overhead lighting. Typically, when using studio flash units, the ambient light will be overpowered by the direct flash. However, it is important to factor in any ambient light in your flash meter readings to ensure a proper exposure.


BCPS (Beam CandlePower/Seconds): Beam Candlepower Seconds is the measure of effective intensity of a light source when it is focused into a beam by a reflector or lens. Beam Candlepower Seconds is the effective intensity for a period of one second.


Bounce Lighting: Bounced light is an indirect light source, where the actual light is pointed away from that which you wish to illuminate, and bounced off of a reflective surface back towards your subject. This can be achieved in flash photography with reflector panels, umbrellas, and even reflective surfaces such as a wall or ceiling. Bounced light is used when you desire a softer, less harsh light quality than is produced with direct lighting.

Bracketing: When shooting, bracketing is taking several photographs of the exact same scene and setup with different exposure settings both above and below the target setting indicated by the flash meter. As different brands of flash meters vary in their readings for a “correct” exposure, bracketing both above and below the indicated settings will ensure that you get a properly exposed picture. If for example, the indicated exposure for a setup is f5.6 with a shutter speed of 1/60 second, you can bracket for one stop less at f8, and one stop more at f4.

Color Balance/Color Temperature (see also Kelvin): The Color Temperature refers to the color of a light source, measured in Kelvin. The Color Balance refers to the relationship between the color of light and the film.

Contrast: The contrast is the degree of difference between the dark and the light areas of a scene or photograph. High contrast photographs are a result of high contrast lighting, where there are sharp differences in the dark and light, and less in between. High contrast lighting can be achieved with both direct and bounced light that is not softened or diffused but often reflected from a bright silver surface.

Depth of Field: The depth of field refers to the nearest and farthest points in your photograph that are in focus in your shot. A lens can only focus on one single distance fully, but with a wide depth of field, areas both closer and further from that one point are relatively in focus as well. Stopping down to a smaller aperture increases the depth of field, and will result in more of the photograph being in focus.

Diffused Light: Diffused light is softened light, with less shadows and more even coverage. A diffused light source is most commonly achieved by directing light through a translucent material, such as a diffusion shoot-through umbrella, a softbox, or a diffusion reflector panel.

Effective Wattseconds: This terminology was originally used in 1985 by Inverse Square Systems in conjunction with their “Stroblox” series of high-efficiency self-contained flash units. The term was created because most manufacturers of flash equipment (as well as the press) insisted on the incorrect use of the term “wattsecond” as a definition of light output (in such wrong statements as “This system puts out 800ws of light”). Since the Stroblox system produced on the order of twice the amount of light per wattsecond as did the average “box-and-cable” system at the time, Inverse Square Systems chose to employ the rating “2400 effective wattseconds” as a means of saying “our system puts out an amount of light equal to the average 2400ws system,” even though the actual stored energy of the Stroblox 2400 was only 1200 joules or wattseconds. Indeed, this terminology gave the user a more clear idea of what to expect from the unit than he would have gotten had they simply stated that it was a 1200ws system. We publish wattseconds, effective wattseconds, and Lumenseconds for our flash units, with Lumenseconds being the most valuable method of power comparison.

Fill Light: In a lighting setup, the fill light refers to the light source which is used to “fill in” the shadows cast by the main light. This source can be a flash unit, or simply a reflector that is directed on the subject to illuminate the shadowed areas and lessen the contrast.

Filter/Gel: A filter or gel for a flash unit is a thin piece of tinted or colored gelatin placed directly over the light source to alter the quality of the light’s output. Gels will physically change the color of the light, whereas filters will modify its quality. We offer color gels, warming filters, diffusion filters, UV filters, and neutral density filters.

Flash Duration (t.1, t.3, t.5): When a flash system fires, although it may appear so to humans, the light emitted does not come on and go off instantaneously. In reality, the flash tube ‘turns on’ very quickly and then dims gradually as the flash capacitors discharge. Short flash durations are important to prevent blurring when the subject is in rapid motion such as a pirouetting ballerina or a Michael Jordan slam-dunk. Flash manufacturers do not rate flash duration as the entire time the flash tube is emitting light, however, because the end of the slowly dimming ‘tail’ does not contribute much to the overall exposure (or to blur). t.1 is defined as the time during which the flash lamp output is above 0.1 (or 1/10) it’s peak intensity. t.3 you may guess is the time the output is greater than 0.3 (about 1/3) peak, and t.5 is how long it’s above 0.5 (half) the peak value.

F-stop: An f-stop is a designation to indicate a camera’s aperture opening, and a flash unit’s power level. Our flash units are measured in power over a range of available f-stops, indicating the high or low power level setting of the unit. Each f-stop (shown on the back panel of our flash units) lets in twice as much light as the f-stop before it, and half as much light as the f-stop after it. Over a 5 f-stop range, the power is adjustable from Full down to 1/32 of the total power. For f-stops in relation to your camera’s lens opening, see aperture.

Guide Number: The Guide Number is another way of stating BCPS. The Guide number tells you what aperture setting you will need on the camera for a given light to subject distance at a given film speed. For example, if you are using an ISO 100 film, you would use the ISO 100 GN and divide this number by the distance from light to subject to find the correct lens aperture. If for example, the ISO 100 GN for your flash were 110, and your subject were 10 feet from the flash, you would use an f11 aperture. By looking at an appropriate chart, you could also find that an ISO 100 GN of 110 is simply another way of stating a rating of 2800 BCPS. Like the BCPS rating, the Guide Number only has relevance when the flash is used direct.

Highlight/Hot Spot: Highlights or hot spots are very bright, well-lit and often overly lit areas in your setup, causing a very dense, dark spot on your negative. Hot spots appear when one area of your scene is overly lit, and can be avoided by diffusing or lowering the output of light on that area.

Hot Shoe: A hot shoe is a u-shaped mounting point, usually found on the top of 35mm SLR cameras. This feature provides a slide-in mounting of small, battery operated flash units. In addition, it provides an electrical circuit connection which fires the flash when the shutter is tripped. If your camera does not have the necessary PC connection to wire our flash unit sync cord, you can purchase a hot shoe adapter piece, which fits in your hot shoe, and allows the sync cord to be plugged into your camera.

IEC Standard Connector: An IEC is a standard connector system for removable power cords on electronic equipment. These power cords are found on just about all computer equipment and are also widely used in electronic test equipment. This connector system is used on Ultra flash systems.

ISO: An ISO number rating refers to the speed of the chosen film. A lower ISO film, such as 100-speed film, will require more light. A higher ISO film, such as 400-speed film, will require less light, but produce grainier negatives. The higher the ISO, the less light required. Typically, lower speed films are used for portraits, whereas higher speed films are used in lower light settings or in sports photography where one wishes to stop action.

Joules: Joules are a measurement of output, rated the same as true wattseconds. See wattseconds.

Kelvin (K): The Kelvin is a unit of temperature measurement starting from absolute zero at -273 Celsius. Degrees Kelvin (or color temperature) is used in color photography to indicate the color balance or spectrum of light emitted from a light source. If you were to heat a chunk of iron to 3000º Kelvin, the light emitted from the iron (a dull red glow) would be said to have a color temperature of 3000K for the purposes of color photography. Sunlight measures about 5500K and film balanced for sunlight (daylight film), will assure ‘true’ color rendition for objects reflecting the sun. Photographic, or Xenon, flash creates a light source with a color temperature of about 6000K. AlienBee flash units come with a standard flash tube which measures 5600K and is daylight-balanced for film. We also offer optional UV-coated tubes, rated at 5200K.

Lens Flare/Light Spill: With ambient and studio lighting, when light is directed or refracted into the camera’s lens, this light is known as lens flare. Some photographers will allow light to be reflected in their camera’s lens for an intended glowing effect, but normally light spill is undesired. When using studio lighting to illuminate your subject, you can eliminate light spill by position your flash unit and accessories to not direct light back into your camera.

Lumensecond: A Lumen is a unit of measurement of light intensity falling on a surface. A Lumensecond refers to a light of 1 Lumen intensity for a duration of one second, or the equivalent, such as 2 Lumens for half a second. The absolute amount of light emitted each time a flash system is fired is correctly specified in lumenseconds. The number of lumenseconds produced by a particular flash system depends on the efficacy, how effectively the system turns electrical energy into light energy, or wattseconds into lumenseconds. The efficacies of commercial photoflash systems typically fall within the range of from 15 to 50 lumenseconds per wattsecond. What this implies is quite simple: a highly efficient 300ws system may produce as much actual light energy as an inefficient system rated at 1000ws.

Main Light: The main light in a lighting setup is the primary light used. This primary light source is typically the brightest in your setup, casting the most prominent shadows.

Manual Exposure: Manual exposure is a camera mode which is non-automatic, and requires the photographer to set their own aperture and f-stop for each shot. This mode does not rely on the camera’s internal metering system but requires to take a reading with a separate flashmeter to determine correct settings. When using external flash units, your camera should be adjusted manually.

Monolight: The terms ‘monolight’ and ‘flash unit’ are often used interchangeably. A monolight is self-contained flash system, that incorporates the power supply and flash head in one package. This term is used to distinguish these systems from ‘power pack’ systems where the power supply and flash head are separate and are connected using a heavy duty, custom cable. Monolights draw their power directly from standard wall outlets.

Proportional Modeling System: The modeling system aids the photographer in the composition of a shot by providing a continuously burning light source that imitates (models) the flash illumination. In order to be defined as proportional, the modeling light must imitate the flash in two important respects. First, it must provide the same pattern with various modifiers (reflectors, softboxes, barn doors). Secondly, it must accurately track the flashpower in order to show lighting ratios when two or more lights are used in a setup.

Recycle: When you fire your flash unit, it releases all of the energy stored in its flash capacitors in order to emit the flash of light. Before you can fire the unit again, the capacitors must have time to recycle, or build up enough energy in the capacitors in order to fire again. AlienBee flash units boast extremely fast recycle times, which are lessened as you decrease the flashpower. On the X-Series X800 unit, for example, the unit may be used at full power and will recycle in under 1 second! Fast recycle times are important for rapid shooting, as you can take shot after shot without pausing to wait for your flash unit to keep up.

Shutter Speed: Shutter speed is a term which refers to the length of time your camera’s shutter is open. As the shutter opens and closes to expose your film, the shutter speed measures in seconds the length that light is reaching your film. Obviously, the longer the shutter speed, the more light you are letting in. Very fast shutter speeds will allow you to stop action, but require a great deal of light.

Slave: A flash unit is said to be a slave flash when it is set up to fire by detecting the flash from another (master) flash unit in a multi-light setup. This allows multiple light setups to be operated with only one light synchronized (wired) to the camera. As many slaves as necessary can be used in a set-up. All studio flash units from Paul C. Buff Inc. have highly sensitive built-in slaves which can be disabled if desired.

Sync: The sync connection in a flash system connects to the camera body, either to a PC connector or through the hot shoe. This circuit is used by the camera to fire the flash at the precise moment that the shutter has fully opened and before it begins to close to successfully capture the full light burst from a flash set-up.

Through-The-Lens Meter (TTL): A TTL meter is a light/exposure meter which is built into your camera, and takes light readings through the lens to determine the correct settings when in automatic mode. Often, this meter sends out a pre-flash or infrared sensor in order to detect the amount of available light. This signal may inadvertently trip your unit’s built-in slave tripper, and therefore can not be used with flash units.

Wattseconds (Joules): A wattsecond is a measure of electrical energy used in flash systems to indicate the amount of energy in the flash capacitors. Since this is only a measure of electrical energy and does not take into account considerations such as flashtube efficacy, or flash capacitor/flashtube energy transfer efficiency, it is not necessarily a good number to comparatively assess light output. See also effective wattseconds and Lumenseconds.

La terminología se define como el campo de estudio interdisciplinario que se nutre de un conjunto específico de conocimientos conceptualizado en otras disciplinas: En este caso hablaremos de la fotografía