Glossary of photographic gobbledygook.
Welcome to SL - Photography. Please note that all images are © Steve Lavington, all rights reserved.
Here's a list of terms commonly used in photography. Please note that this is a work in progress, and that the definitions are my interpretations and not necessarily fact.
Aperture - controls the amount of light reaching the sensor, and in combination with shutter speed determines the sensor's exposure to light. Expressed in an f/ number, where the smaller figure means a larger/faster/wider aperture, because it lets in more light.
Av - aperture priority mode, where the user selects the aperture and the camera determines the correct shutter speed.
BG - background.
Bokeh - the appearance of out of focus areas - so 'good bokeh' could be an aesthetically pleasing out of focus background.
Camera shake - the inevitable 'shake' seen through the viewfinder - especially when using longer lenses, which magnify the shake - caused by hand tremors, breathing and so on from the user. It can be reduced by a good handholding technique - this is discussed in the 'getting it right' article.
Colour temperature / white balance - the 'warmth' or 'coolness' of an image, expressed on the Kelvin scale. 5000K produces a warmer image than 3200K, which is cool in comparison, with a bluish tint.
Crop factor - the multiplying effect of a digital sensor in comparison to a film sensor on the focal length of a lens. A full frame camera has the same size sensor as a film camera, so has no crop factor. APS-C size sensors - e.g. the Canon 450D + 40D - have sensors that are smaller, and so the cropping effect of this means the field of view is 1.6X smaller than that of a film sensor. This means a 400mm lens effectively becomes a 640mm lens (400 x 1.6 = 640).
D.O.F - depth of field - the amount of an image that is in acceptable focus, determined by the aperture.
DSLR - digital single reflex camera - one of the most common types of camera, used by almost all professionals. It is given it's name because of the way light enters the camera, and is sent through a pentaprism as well as to the sensor, so the image is viewed in real time through a viewfinder.
Exposure - the amount of light allowed to fall on the camera's sensor, determined by the aperture and shutter speed.
Exposure compensation - used to adjust the exposure. Expressed in +/- stops, whereby + stops will increase the brightness of the image with increasing intensity (+ 2 Ev>+1 Ev), and - stops decrease the brightness of the image with increasing intensity (-2 Ev> -1Ev).
Ev - exposure compensation.
Focal length - the 'reach' of a lens, expressed in millimetres. 50mm is generally seen as the equivalent of the human eye. It is worth noting that differences in focal length are far more noticeable at the wide end of the spectrum - the difference between a photo taken with a 17mm and 21mm would be obvious, whereas the differences between a 400mm and a 420mm would not be so noticeable.
FG - foreground.
ISO - the camera sensor's sensitivity to light, usually ranging from ISO 100 - 1600, but often wider in more expensive cameras.
I.S. - Canon's term for image stabilising. This helps steady the image and thus reduces the effects of camera shake. Sigma and Nikon also have stabilisation systems, called O.S and V.R respectively.
Magnification - This often means different things, but is not how much the image is magnified by compared to the human eye. Generally, it means the range of a zoom lens - i.e. a lens of 20-200mm would have 10X magnification. However, a 200mm lens would only make things 4X closer (50mm = human eye). You would need a 500mm lens to get your subject 10X closer.
Macro - a type of photography that involves close up detail, often of insects or flowers.
M - manual mode, where the user selects both the aperture and shutter speed.
Motion blur - a blur effect whereby the image looks smeared and out of focus, caused by subject or photographer movement.
Noise - random colours and artefacts spread across an image, caused by the selection of a higher ISO number. Almost like the digital equivalent of grain. It can easily spoil an image.
OOF - out of focus.
Overexposure - when an image is overexposed, due to incorrect settings (shutter speed, aperture etc.). Symptoms include white areas appearing 'blown out' or 'clipped' - too bright with little or no detail.
PP - post processing using imaging software such as Photoshop.
PS - Photoshop.
RAW - a format of saving an image that is lossless (not compressed), and has no processing applied on the camera. This gives better control over exposure and allows white balance to be chosen on the computer, but at the cost of much larger file sizes.
Sensor - the part of the camera that is exposed to light and records an image onto the camera's memory / a memory card.
Shutter speed - (a.k.a. exposure time) how long the camera's sensor is exposed to the image by opening the shutter. Expressed as a fraction of a second, e.g. 1/2500.
Telephoto - a long focal length lens, usually ranging from 70 - 300mm. Anything above 300mm is generally called super telephoto.
Tv - shutter priority mode, where the user selects the shutter speed and the camera determines the correct aperture.
Underexposure - when an image is underexposed, due to incorrect settings (shutter speed, aperture etc.). The image appears darker than it should be.
Wide angle - a short focal length lens, that gives an image wider than the view of a human eye, usually from 20 - 50mm. Because of the crop factor, wider lenses are more common, because a 28mm lens, which would be seen as wide angle on a film camera, becomes a much longer 45mm on most DSLR's.