A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. S. T. U. V. W. X. Y. Z.

Aperture: The aperture is a circular opening in the lens of your camera. It is controlled by an iris diaphragm to vary the diameter. It is adjusted to open and close in f-stops. By adjusting the iris diaphragm the amount of light that will reach your film or sensor is controlled by making the opening larger or smaller. Each aperture opening is known as an f-stop and each f-stop lets in twice as much light as the smaller f-stop before it, or half as much light as the larger f-stop after it.
So, f5.6 will let in twice as much light as f8, and half as much light as f4.

Automatic Mode/Automatic Exposure: As a professional photographer you would, of course, never have to use the 'Automatic' mode on your camera. Here is why ytou should especially not use it when shooting with Bowens (or any other manufacturer) monolights - the automatic mode relies on the cameras TTL (Thru the lens) metering system which is unable to detect the flash that will come from the monolights, so the auto settings will be wrong and will result in horribly over-exposed images.

Available Light: Available light or sometimes refered to as ambient light is light that is already present where you plan to shoot such as the Sun or domestic lighting.
Usually, when you are using Bowens studio flash units, the available light will be overpowered by the direct flash. You should switch off any ambient lighting and block out that nasty sun before taking meter readings or at least remember that the other light is there and take it into account.

Bounce Lighting: Bounced lighting can be used to create a very soft fill-in light using products such as the Bowens Reflector Discs - which can be used in portraiture, indoors our ourdoors, to reflect light from flash or even the Sun to fill in shadows. You can also bounce light from ceilings or white walls to acheive the same soft effect..

Bracketing: Bracketing is when you take several versions of a shot at exposures either side of that determined by the flash meter giving different levels of exposure. It is good practice as, even with todays advanced image tweaking software, if when reviewing your pictures you decide the image should have been slightly over or under exposed you will already have those images and not have to set the shot up again. Some Bowens generators have auto bracketing options built-in to make photographers lives simple.

Colour Balance. Usually for film. This refers to the lighting conditions to which the film is designed to record images, typically expressed as either daylight (5500K) or Tungsten (3200K).

Colour Temperature. Colour temperature is a way of defining the colour of a light source - usually refered to in Kelvin. The Kelvin absolute scale defines the temperature to which a black metal rod would need to be heated to match the colour of the light source.

Contrast: Contrast is the difference between extremes of light and dark in an image. High contrast is when there is a very sharp difference between the lightest and darkest areas and not much inbetween. Bowens manufacture several reflectors which can be used to create high contrast and high key images.

Depth of Field: Depth of field is the distance between the nearest and furthest parts of a subject which can be recorded in an acceptable focus at one setting of your camera. Depth of field can be increased by using a smaller aperture so that more of your image is in focus, conversly if you use a larger aperture you will decrease your depth of field so that only one part of your image will be focused with the rest of the image blurred - which is a popular effect.

Diffused Light: Diffused light is often very soft and even with very minimal shadows. The best way to acheive diffused light is, as the name would suggest, to use a diffuser such as a Bowens softbox, or by removing the silver cover of a Bowens umbrella and shooting through the white diffuser material.

Fill Light: The fill light is designed to fill in areas not covered by your main light so that you do have glaring and very obvious shadows in your photo. Fill in light can be created by using flash or just be reflecting ambient light using a Bowens reflector disc.

Filter/Gel: Filters and gels fit over the light source to change the colour or quality of the light. Many Bowens reflectors are designed specifically to be used with Gels and Filters - we also manufacture the Bowens Multiclip which can be used to attache gels and filters to just about anything.

Flash Duration (t=0.1, t=0.3, t=0.5): When a studio strobe 'flashes' the flash tube turns on very quickly and then dims gradually as the flash capacitors discharge. If your subject is in rapid motion then you will need a fast flash duration to prevent your image being blurred. Because the light emmited by the dimming end of the 'flash' does not really contribute to the exposure, we do not rate flash duration as the entire time the flash tube is on - instead, when you read out technical specifications you will not that we use t=0.5 which is the amount of time that the output of the flash is above half of the peak value. t.1 is the time during which the output is above 1/10 of it's peak and t.3 is the time the output is greater than 1/3 peak.

F-stop: F-stops are an international standard sequence of numbers which express relative aperture - lens focal length divided by the effective aperture diameter. Each chnge of F-stop halves or doubles the image brightness, as you 'step' up or down.

Guide Number: The guide number of a flash gives you an indication of what f-stop to set your camera to given the distance of the subject from the light source To do this you simply need to divide the guide number by the distance between your flash and subject. The distances are usually measured in meters.

Hot Shoe: The hot shoe is an accessory shoe built into the top of most professional cameras incorporating electrical contacts which allow you to usually add flash guns desigend by the camera manufacturer. Bowens use the hot shoe to mount our Pulsar Radio Trigger which allows remote flashing of our lights via a radio signal so you don't need sync cables.

Hot Spot: A hot spot is an area in the middle of a pool of light where the light is very intense - hot spots can be elliminated by using diffusers. Some Bowens accessories include special diffusers which are printed with a complex pattern to ensure that light is distributed evenly across the subject eliminating the hot spit all together.

IEC Standard Connector: These power cords are found on just about all computer equipment and are commonly referred to as 'kettle power cords'. This connector system is used on Bowens equipment.

ISO: International Standards Organisation. In Photography the ISO 'number' usually relates to the speed of film (or equivilant on digital cameras). The lower the speed of the film the more light is required. So in the same way that you need a fast flash duration to capture movement, you would need a higher ISO speed.

Joules: Joules are a measurement of output, rated the same as wattseconds (Ws). At Bowens we always refer to the output of a unit in Ws.

Kelvin (K): The Kelvin is a unit of temperature measurement devised by the scientist Lord Kelvin. It starts from absolute zero at -273 Celsius. Degrees Kelvin (or colour temperature) is used to meausre the colour balance of light emitted from a light source. The Kelvin absolute scale defines the temperature to which a black metal rod would need to be heated to match the colour of the light source. Sunlight measures about 5500K and film balanced for sunlight (daylight film), will assure 'true' colour rendition for objects reflecting the sun. Bowens Esprit 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: Sometimes ambient light or even flash light is reflected bsck on to the lens of your camera, this is know as lens flare. Occasionally this effect is desired, but more usually it is unwanted, changing the angle at which you are shooting or the angle of the lights can often solve this, other ways of reducing lens flare or light spill include using barn doors or flags.

Main Light: The main is the primary light used in your lighting set-up usually the brightest in your setup.

Monolight: A Monolight is self-contained flash system, invented by Bowens in the 1960's, that incorporates the power supply and flash head in one package. We used this term to distinguish our self-contained flash systems from our 'generator' (or power pack) systems where the power supply and flash head are separate and are connected using a heavy duty cables. Monolights on the other hand are able to draw their power directly from standard mains power sockets.

Proportional Modeling System: Bowens Flash Units feature proportional modelling. This is a system designed to aid the photographer to set up a shot by mimicking the out put of the flash in a continuous manner in both output and effect allowing you to see where shadows and highlights will fall when you take the shot.

Recycle: When flash unit fires, it releases all of the energy stored in the capacitors. Before the unit can be fired again the capacitors must have time to build up enough energy in order to fire again, this is known as recycling. Fast recycle times are important for rapid shooting as you do not need to wait excessively for the power to recharge. Bowens QUADX generator boasts a masive 3000Ws of power with recycling as fast as 0.4 seconds and flash durations a quick as 1/7100 sec!

Shutter Speed: Shutter speed is the length of time the cameras shutter is open. As the shutter opens and closes to expose your film or image sensor the time in seconds that light is reaching your film or sensor is the shutter speed. The longer the shutter is open, the more light is let in. In order to acheive stop action, you need a very fast shutter speed.

Slave: All Bowens Esprit Flash & QUAD generators feature sensitive built-in slave cells which can be switched on or off as you require. This feature means that you only need to sync your camera to one light - the other lights in your setup then become 'slaves' and will fire when your main light does.

Sync: The sync connection on Bowens equipment allows you to connect the flash to your camera using the PC socket. With this connection the flash unit will fire when the cameras shutter is fully open in order to capture the optimum light from the flash.

Through-The-Lens Meter (TTL): TTL metering is built-in to most professional cameras and measures the direct light available in order to determine the correct camera settings - often in automatic mode. As mentioned above, this cannot be used when using studio lighting as the flash cannot be measured by the TTL meter.

Wattseconds (Joules): A wattsecond (Ws) is a measure of electrical energy which we use to indicate the amount of energy in our flash units. This can be used to measure the performance of one unit against another - although many people prefer to use the guide number for this comparative purpose.