ambient light– The available natural light completely surrounding a subject. Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer i.e. not by artificial light source.

aperture– the hole in a lens through which light travels. determines depth-of-field. measured in stops (f/2.8, f/8, etc.).

bulb–  setting on a camera (B on the shutter speed dial) which allows the shutter to be open for as long as the shutter release is held down, usually using a cable release. similar to a ‘T’ setting (time) where the shutter opens on the first press on the shutter and closes with the second press of the shutter release.

CCD– (charge-coupled device) a device in digital cameras that converts colors into a digital value. When you read ‘3CCDs’ (mostly in video cameras) it means there is a CCD for each primary color (RGB). This came about in the late 1800’s when photographers would make a glass plate negative for each of these colors, which would be overlayed to make a color image.

chimping– reviewing a digital image on the LCD screen immediately after shooting, oftentimes before the rider has landed the trick being shot.

chromatic abberation– the purple-ish fringing around contrasty areas in a digital image, usually caused by poor optics.

CMOS– (complementary metal-oxide-semiconductor) a device, much like a CCD, that can automatically convert light waves into into digital values via a large array of pixel sensors all of which also containing their own detector and amplifier.

depth of field– the part of a photograph that is in focus. determined by focal length, aperture and image format. wider lenses have an inheritly deeper depth of field, while longer focal lengths have a more shallow depth of field. this is why you can get a more blurred background, sharp object artsy type image when using a 50mm or 85mm lens at wide open apertures (f/1.4 or f/1.8) while wider lenses allow more of the image to be in focus at once. try shooting at the same aperture with a wider lens and a longer lens– there will be much more in focus with the wider lens at any given aperture than with a longer lens. I highly suggest you read up on this subject if you refer to yourself as a photographer.

f/stop– A fraction which indicates the actual diameter of the aperture: the “f” represents the lens focal length, the slash means “divided by,” and the word “stop” is a particular f-number; for example, with a 50mm f/1.4 lens, the actual diameter of its maximum aperture is 50mm divided by 1.4 or 35.7mm; at f/2, the diameter becomes 50mm/2 or 25mm; at f/2.8, the aperture is 50mm/2.8 or 17.9mm across; as the numerical value of the f/stop increases, the aperture decreases in size.

fill flash – the flash (in a three-point lighting setup) designated to fill in any shadows incurred by the key and/or rim light. Usually metered one stop under the base exposure of the image (e.g. you’re shooting f/8, fill is f/5.6)

flash synchronization– Timing of the flash coincides with release of the camera’s shutter. There are two types of synchronization: Front-Curtain Sync, which fires the flash at the start of the exposure, and Rear-Curtain Sync, which fires the flash at the end of the exposure.

flash sync speed– (x-sync) the fastest shutter speed that a camera can fire a flash and have and expose while the flash is still firing. Most cameras have a sync of 1/250th, others having up to 1/500th or just 1/60th.

guide number– (GN) a method used to express the power of a flash. Determined by multiplying the flash-to-subject distance (usually 10 feet) by the f/stop needed to get a correct exposure. you don’t really need to know the mathematics, just that the higher GN, the more powerful the flash is. watch out though because sometimes the GN is measured in meters, not feet (america, fuck yeah)

HDRHigh Dynamic Range – a method used by shooting the same image three times (correctly exposed, underexposed and overexposed) then blended together on a computer, achieving an image with no blocked-out shadows and no blown-out highlights.

hyperfocal distance– a distance that when focused at produces the maximum depth of field- everything from half of that distance to infinity and beyond will be in ‘acceptable’ focus. this distance is determined by a given focal length at a given aperture. very helpful when shooting with a fisheye lens. use this calculator to find the hyperfocal distance that is right for you.

incident light– Light falling on a surface as opposed to the light reflected by it.

ISO– (International Standards Organization) a unit of measure to rate film speed. higher ISO require less light, but at the cost of image quality. For the most part, you will want to use a lower ISO for cleaner looking photographs.

K– Kelvin. A scale used to measure color temperature. 5500K = noontime sunlight  2800K = generic tungsten lightbulb 

key flash – The flash (in a three-point lighting setup) which provides the principal illumination on a subject. Usually metered at the base exposure of the photograph (compared to fill being one stop under and rim being one stop over).

parfocal– the ability of some zoom lenses to hold their focus while zooming in/out (see also: varifocal)

push processing– Increasing the development time of a film to increase its effective speed for low-light situations

rim flash – the flash (in a three-point lighting setup) which contributes a highlight on one side of the subject, in order to separate them from the background. Usually metered at one stop over the base exposure (e.g. you’re shooting at f/8 while rim flash is outputting f/11).

RMS granularity- (root mean square) A method invented by Kodak to express the amount of grain in any given film. The lower the number is, the finer the grain. Underexposed film has more grain than correctly or overexposed film does.

shutter speed– the amount of time the film or sensor is exposed to light while the shutters open and close. the speed is usually a fraction of a second (1/60th, 1/500th).

trickle charge– to charge a battery back to full capacity without the battery having been used. Most batteries lose a charge at a slow rate even when they are not being used. Lithium batteries self-discharge at a rate of around 2-3% per month whereas nickel-based batteries go from 15% to 30% per month.

TTL– through the lens. a term used with flashes meaning the ability to automatically set the power of the flash from the meter reading on your camera. not recommended for action photos. always use manual settings.

varifocal– the tendency of some zoom lenses to change the point of focus while zooming in/out (see also: parfocal)

vignetting– Underexposure of image corners produced deliberately by shading or unintentionally by inappropriate equipment, such as unsuitable lens hood or badly designed lens. A common fault of wide-angle lenses, owing to reflection cut-off, etc. of some of the very oblique rays. May be caused in some long-focus lenses by the length of the lens barrel.

white balance– a color temperature, ranging from blue (cold) to yellow (warm). measured in kelvins (K). the color temperature at noon is 5500K. an incandescent lightbulb has a temperature around 2800K.

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