Aperture:
The opening in a lens through which light passes to expose the image sensor or the film with analogue camera. The size of the aperture hole is referred to f-stops. The larger the f-stop number, the smaller the lens opening, and the more depth of field you will receive in a photograph. Also the larger the f-stop number, the slower the shutter must be.
Aperture Priority:
Feature of a camera where the aperture is set to a fixed f-stop, and the camera chooses the corresponding shutter speed for a correct exposure. This is useful for controlling the depth of field.
Aliasing:
Effect of visual stair-stepping of edges of diagonal lines, edges of circles, etc because pixels that make up a digital picture are square.
Ambient light:
The natural available light in a scene, for example the light from the sun through a window.
Anti-Aliasing:
Technique that smooths out hard edges of aliasing by averaging out the pixels around the edge.
Artifacts:
Unwanted differences from the original image caused by lossy image compression. With lossy image compression, the more compression, the more artifacts are visible.
Asymmetry:
An image that is not identical on both sides and not centered in the middle third is asymmetric. Opposite of symmetry.
Auto Exposure:
The camera automatically chooses the best combination of aperture and shutter speed for a correct exposure. This can be Aperture Priority (where the aperture is fixed), Shutter Priority (shutter time is fixed) or Program/ Full Auto (the camera chooses both aperture and shutter speed).
Auto White Balance:
Feature of a camera that automatically sets the white balance to match the color hue of the subject based on the lighting situation.
Auto Focus:
A system of lens and camera that automatically focuses before the exposure is made.
Backlighting:
Lighting that comes from behind the subject and towards the camera lens. This can produce a silhouette of the subject.
Background:
Plane of space in a picture behind the subject, as opposed to foreground and mid-ground/ subject.
Barn doors:
Accessory for controlling the direction and width of the light beam of studio lights.
Barrel distortion:
A lens aberration where parallel lines at the edge of the image area appear to bow outwards.
Bokeh:
Bokeh describes the quality of out-of-focus areas of an image. The word “bokeh” (pronounced as boh-keh) comes from the Japanese word “boke” which means fuzziness. Bokeh isn’t the depth of field itself, but the way this unsharpness (usually the background) is displayed on a picture. A lens has good bokeh if the out-of-focus areas are pleasant and don’t distract from the subject. The shape of the aperture of a lens has a influence on bokeh. Lenses with more blades in the aperture diaphragm tend to result in more “round” bokeh.
Bracketing:
The technique of taking a number of images of at different levels of exposure. For example taking one photo 1 stop under exposed, one with the calculated right exposure, and one photo 1 stop over exposed.
Buffer:
Memory in the camera that stores digital photos temporary before writing to the memory card.
Bulb Mode:
Setting on which the shutter stays open as long as the release is pressed. Used for very long exposures.
Burning:
Selectively darkening parts of a photo. With analogue photography this was done in the darkroom by allowing more light to reach parts of the printing paper. With digital photography this is done with photo editing software like Adobe Photoshop or Paint Shop Pro.
Burst Mode:
Feature of a camera that allows take one picture after another as long as the shutter release button is held down.
Cable release:
Cable for triggering the shutter. Useful with long exposures for avoiding camera shake because of touching the camera.
CCD:
Charge Coupled Device; the sensor inside the digital camera that actually captures the picture.
Chromatic Aberration:
Purple fringing that occurs because the image sensor doesn’t capture the different colors (wave lengths) on the same focal plane through the lens. Can be caused by the lens optics.
CMOS Image Sensor:
Image sensor created using a Complementary Metal-Oxide Semiconductor (CMOS).
CMYK:
A color model based on four process colors: Cyan, Magenta, Yellow, and Black in which all colors are described. Used to optimize images for printing as a mixture of these four colors.
Compact digital Camera:
A small and easy to use non-SLR digital camera designed for simple operation, having many automated functions. Popular compact digital cameras include the Canon PowerShot, Sony CyberShot, Fuji FinePix and Nikon Coolpix.
Compression:
Process of reducing the size of a digital image using software algorithms. This process can remove details from an image.
Continuous shutter:
See burst mode.
Cropping:
Photo editing technique where a part of a photograph is removed.
Crop factor:
Most DSLR (Digital Single Lens Reflex) cameras have image sensors that are smaller than a the 35mm film frame.The crop factor of a camera is the size 35mm film frame compared to the size of the image sensor of the camera. When using lenses of an analogue SLR the “35mm Equivalent” focal length of the lens is the focal length of the lens multiplied with the crop factor. A typical crop factor for Canon is 1.6 (for the Canon EOS 350D/ Digital Rebel XT and Canon EOS 30D) and 1.5 for Nikon (for the Nikon D50, Nikon D70, Nikon D70s and Nikon D200).
Full Frame digital SLR:
A digital SLR with an image sensors that has the size of a 35mm film frame. The crop factor therefore is 1. Popular full-frame digital cameras include the Canon EOS 5d and the Canon EOS-1Ds Mark II.
Depth of field:
The area of a photograph that is in focus.
Digital SLR:
A digital SLR is a SLR (Single Lens Reflex) camera that records photos digitally instead of film.
Digital zoom:
Feature of a digital camera that magnifies an image by discarding the pixels on the edge of the image and enlarging the center of the center area. This mimics a greater zoom but doesn’t gain any additional image detail.
Dodging:
Selectively lightening part of a photo.
EXIF:
EXIF (Exchangeable Image File) is the most common file format for digital cameras.
Digital cameras usually record an EXIF file that uses JPEG compression to compress the image data within the file.
Exposure:
The quantity of light that your camera captures while taking a picture. The exposure is determined by the aperture size and shutter speed. To obtain the best results with certain subjects it may be necessary to alter the exposure from the value suggested by the camera. An exposure compensation button [+/-] is now found on most modern auto cameras. Positive compensation may be needed when the main subject is darker than the background and negative compensation may be needed for a subject lighter than the background.
Exposure compensation:
Setting of a camera for intentionally under- or over-expose a photo shot.
Fill flash:
Flash technique for brightening shadow areas on the subject, typically outdoors on sunny days.
Fish-eye lens:
An extremely wide-angle lens that enables views exceeding 100 degrees up to 180 degrees, but distorts the image.
Flare:
Series of bright polygons scattered by reflections within a lens or camera interior. Lens flare can occur when shooting directly at the sun or bright light.
Flash range:
The distance over which a flash can give adequate illumination.
F-number:
The f-number or focal ratio of an lens is the diameter of the lens opening in terms of the effective focal length of the lens. Common f-numbers are f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, and f22. The greater the f-number, the smaller the aperture and the less light will pass the shutter.
Focusing:
Adjustment of the lens of the camera to bring the subject into sharp view.
Foreground:
Foremost plane of space in a picture, as opposed to mid-ground and background.
Front Lighting:
Lighting that shines on the subject from the front.
Gamut:
Range of colors that a device can be capture or display.
High key:
An image that contains large areas of light tones and little mid-tones or shadows.
Histogram:
A two-dimensional graphic representation level of occurrence in a photo of the range of tones from dark to light with horizontal the brightness and vertical the number of pixels.
Useful for checking if the image is under or overexposed.
Hue:
The dominant wavelength of light and distinguishes red from green and blue from orange, etc.
Image Resolution:
See Resolution.
Image Stabilization:
IS (Image Stabilization) is used in cameras to reduce the effects of shake caused by not holding the camera steady with handheld shots. Optical image stabilization employs a floating optical element and a fast spinning gyroscope mechanism to steady the projection back into the camera. Canon lenses with image stabilization have “IS” in their name, like the Canon EF 70-200mm f/2.8L IS USM and EF 70-300mm ƒ/4-5.6 IS USM. Nikon uses the term “VR” (for Vibration Reduction), like the 70-200mm ƒ/2.8G ED-IF AF-S VR Zoom-Nikkor. Optical stabilization is also used in compact digital cameras from Panasonic, Canon, Kodak, Konica Minolta, Nikon and Sony.With CCD-shift stabilization the system shifts the image sensor itself. It is used in the Konica Minolta DiMAGE and MAXXUM Anti-Shake, Pentax’s Shake-Reduction, and Ricoh Vibration Correction cameras.
ISO speed:
ISO (International Standards Organization) is a measure of light sensitivity based on an arithmetical progression. ISO 200 film is twice as fast as ISO 100 film but only half as fast as ISO 400. The scale is identical to ASA (American Standards Association). Generally, with higher ISO speeds there is more noise.
JPEG:
JPEG (Joint Photographic Experts Group) is the most common file compression method used in digital photography. JPEG uses lossy compression that results in the loss of image data when the image is saved. Saving a JPEG image with high compression can give artifacts on the image.
Lag time:
Time that a digital camera takes between when the shutter is pressed and when the picture is actually captured.
Long lens:
Lens with a large focal length, for example 300mm.
Low key:
An image that contains large areas of dark tones and little mid-tones or highlights.
Macro lens:
A lens that is made for extreme close-up photography to capture small subjects big on the image.
Metering:
The process of measuring the available light reflected from the subject to calculate the proper shutter speed or aperture.
Mid-ground:
The plane of space in the middle of the photograph, as opposed to foreground and background.
Optical zoom:
Optical zoom varies the focal length of a lens, and therefore subject magnification. Optical zoom gives better quality than digital zoom.
Panning:
Photography technique used to follow a moving subject when taking a photo. This creates a blurred background but keeps the subject sharp, which gives a sense of motion to the photo.
Pincushion distortion:
A lens aberration where parallel lines at the edge of the image area appear to bow inwards.
Pinhole camera:
Camera without a lens, but with a small hole of about 0.02 inches (0.5mm) or less.
Point-and-shoot camera:
Easy to use camera by offering maximum automation and few options.
Posterization:
The visible banding effect when a photographic image is displayed due to the lack of colors or shades of gray in a picture.
RAW:
Image format with data as it comes directly off the CCD without camera processing.
Resolution:
Number of pixels in a digital photo (width x height).
RGB:
Red, Green, Blue, the three primary colours in additive colour theory. By mixing Red, Green and Blue a large part of the visible spectrum can be represented.
Rule of thirds:
Composition rule that divides the frame into nine equal areas. Subjects could be placed along one of the lines or at an intersection.
Saturation:
Level of color intensity. It measures the amount of grey in a color given a level of brightness.
Sepia tone:
A brownish colored, old-fashioned effect to an image.
Sharpening:
Increasing the optical illusion of sharpness of an image by increasing the contrast between the adjacent tones or colors. Sharpening cannot create details beyond the resolution of the image, but it brings out the captured detail.
Shutter:
Blades or a curtain that, when open, expose light to the image sensor or film.
Shutter Speed:
The length of time the shutter stays open and image sensor is exposed to light. This can range from fraction of a second (1/500, 1/80) to a few seconds (8s).
Shutter Priority:
Feature of a camera where the shutter speed is set to a fixed time, and the camera chooses the corresponding aperture for a correct exposure. This is useful for adding or avoiding motion blur.
SLR:
SLR (Single Lens Reflex) is a camera type in which one lens is used both for viewing and taking the picture thanks to a system of mirrors and prisms.
Spot meter:
Exposure meter used to take light readings from a small area of a subject.
Stop down:
Changing the lens aperture to a smaller opening. This increases depth of field.
Symmetry:
An image that is not identical on both sides and not centered in the middle third is asymmetric. Opposite of symmetry.
Tilt and Shift lens:
Special lens that has tilt as well as shift capabilities. With tilt movements the focus plane can be made not perpendicular to the sensor plane. It can obtain a wide depth of field even at the maximum aperture and still keep the entire subject in focus. Shift movements reduce the trapezoidal effect of perspective. Tilt and shift lenses are suitable for photography of products and architecture where precise depth of field and perspective control are necessary.
Tripod:
A portable, three-legged stand for providing a steady base for a camera. Good for taking long exposures or studio work. Popular manufacturers include Slik, Velbon, Gitzo, and Bogen/Manfrotto.
Viewfinder:
The part at the back of the camera for framing the shot. It can be an optical viewfinder or a LCD viewfinder.
Vignetting:
Less illumination at the edges of an image. Poor lens quality can be a cause, as well as using the wrong hood for the lens.
White balance:
Adjustment in digital cameras for the color to give as true as possible a white and correcting all the other colors.
Wide-angle lens:
A lens with a short focal length and a larger field of view.
Zoom lens:
Lens with an adjustable focal length that lets you see a scene from a narrow to a wide field of view.