Digital Photography Tutorials » Glossary

Glossary of Digital Photography Terms – Part 6

lau — Wed, 07 Mar 2007 23:00:23 +0000

CCD â€“ (stands for Charge-Coupled Device) is a type of sensor commonly found in consumer level cameras.
CMOS â€“ (stands for Complementary Metal Oxide Semiconductor) is a type of sensor commonly found in more professional level cameras.
Diffuser â€“ is a piece of opaque plastic that sits over the top of a flashgun. It’s job is to soften the light from the flashgun, and therefore reduces harsh shadows caused by a ‘bare’ flash.
Prime Lens â€“ is the opposite of a zoom lens, prime lenses have one fixed focal length. They represent the best quality of lens available, but have the big drawback in that they cannot ‘zoom in’ to a subject.
Purple Fringing – is an undesirable purple “rim” that surrounds areas of high contrast in a digital image, very obvious when photographing people against a bright (but not deep blue) sky.
Shutter Delay – Traditionally, the shutter opened when you pressed the camera’s button, exposed the film behind the shutter, and then closed again; covering the film back over in the process. With electric sensors the “shutter” is controlled by the camera’s computer. A short shutter speed means the sensor is charged for a fraction of a second. For longer shutter speeds, the sensor is kept charged for longer.
Dynamic Range of a Sensor – is defined by the largest possible signal divided by the smallest possible signal it can generate. The largest possible signal is directly proportional to the full well capacity of the pixel. The lowest signal is the noise level when the sensor is not exposed to any light, also called the “noise floor”.
Interpolation – is an imaging method to increase (or decrease) the number of pixels in a digital image. Some digital cameras use interpolation to produce a larger image than the sensor captured or to create digital zoom.
Optical sharpness – is defined by the quality of the lens and the sensor.
Software sharpness – is creating an “optical illusion” of sharpness by making the edges more contrasty.

For more terms, please feel free to send a comment with your suggestions and requests.

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Glossary of Digital Photography Terms – Part 5

lau — Tue, 20 Feb 2007 10:20:33 +0000

Liquid crystal display (LCD) – is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector.
Stock photography – consists of existing photographs that can be used to save valuable time and stay on budget.
Bracketing – is the general technique of taking several shots of the same subject using different camera settings.
Autobracketing – is automatic bracketing by using a setting on the camera to take several bracketed shots (in contrast to the photographer altering the settings by hand between each shot).
Exposure bracketing – the photographer chooses to take one picture at a given exposure, one or two brighter, and one or two darker, in order to select the most satisfactory image.
Focus bracketing – is useful in situations with limited depth of field, such as macro photography, where one may want to make a series of exposures with different positions of the focal plane and then choose the one in which the largest portion of the subject is in focus, or combine the in-focus portions of multiple exposures digitally.
White balance bracketing – provides a way of dealing with mixed lighting by having the camera make several images with different white points for one exposure taken, often ranging from blueish images to reddish images.
Flash bracketing – is a technique of working with electronic flash, when the amount of light provided by the flash is varied in a bracketed series in order to find the most pleasing combination of ambient light and fill flash.

More to come….

Tags: photo, photography, glossary, terms

Glossary of Digital Photography Terms – Part 4

lau — Fri, 02 Feb 2007 20:27:21 +0000

Single-lens reflex (SLR) – is a type of camera that uses a movable mirror placed between the lens to show the image that will be captured in a viewfinder.
Digital single-lens reflex camera (digital SLR or DSLR) – is a digital camera that operates on the same optical and mechanical principles as a film single-lens reflex camera.
Exposure compensation – is a technique to compensate a measured exposure level against other factors which may render a less-optimal image (filters, non-standard processing, or intended under or overexposure).
Focal length – is a measure of how strongly it focuses or diverges light.
Telephoto lens – is a specific construction of a long focal length photographic lens that places its optical centre outside of its physical construction, such that the entire lens assembly is between the optical centre and the focal plane.
Wide-angle lens – is a lens whose focal length is substantially shorter than the focal length of a normal lens for the image size produced by the camera.
Normal lens – is a lens that generates images that are generally held to have a “natural” perspective compared with lenses with longer or shorter focal lengths.
F-number – is the quantitative measure of lens speed, in other words, the diameter of the entrance pupil in terms of the effective focal length of the lens.
Angle of view (Field of view) – describes the vertical and horizontal extent of a given scene that is imaged by a camera.
Viewfinder – is what the photographer looks through to compose, and in many cases to focus, the picture.

more to come….

Tags: photo, photography, glossary, terms

Glossary of Digital Photography Terms – Part 3

lau — Sat, 27 Jan 2007 12:12:29 +0000

Spherical aberration – is the term for an optical fault caused by the spherical form of a lense that produces different focus points along the axis for central and marginal rays.
Curvature of field – optical defect that causes points on an object plane perpendicular to the lens axis to focus on a curved surface rather than a plane.
Astigmatism – aberration in which rays of light from a single point of an object (which is not on the axis of a lense) fail to meet in a single focus thus causing the image of a point to be drawn out into two sharp lines, one radial to the optical axis and another perpendicular to this line, in two different planes near the curvature of field.
Coma – optical defect that causes the image of an off-axis point of light to appear as a comet-shaped blur of light.
Distortion – an rectangle may appear as a barrel or pin cushion-shaped object.
Chromatic aberration – aberration caused by light rays of different wavelengths coming to focus at different distances from the lense.
Aspherical lens – a lens whose curved surface does not conform to the shape of a sphere; because a spherical surface lens has difficulty in correcting distortion in ultra-wideangle lenses or coma in large-aperture lenses brought about by spherical aberration, an aspherical lens is used.
Aspect Ratio – the ratio of width to height in photographic prints – 2:3 in 35 mm pictures to produce photographs most commonly measuring 3.5 x 5 inches or 4 x 6 inches.

more to comeâ€¦.

Tags: photo, photography, glossary, terms

Glossary of Digital Photography Terms – Part 2

lau — Mon, 22 Jan 2007 17:56:20 +0000

Color balance – often refers to the modification of the color values of an image to generate the correct colors on a particular image display or printing device.
Filter – is a camera accessory, a glass or plastic disk with a metal or plastic ring frame, consisting of an optical filter (for different colors: green, blue, red, yellow) that can be inserted in the optical path.
Megapixels – millions of pixels (usually used in reference to the resolution of an image sensor).
Pixel – is a single point in a graphic image.
Optical zoom – uses the optics (lens) of the digital camera to move you closer to your subject.
Digital zoom – simply uses the existing image and enlarges it digitally.
Blur – generally refers to the appearance of an unfocused image.
Gaussian blur – is an effect used to reduce image noise and reduce detail levels.
Red-eye effect – is the common appearance of red eyes on photographs taken with a photographic flash when the flash is too close to the lens (like in compact cameras).
Multiple exposure – is an exposure in which the sensitivity to light is reduced and then increased at least once during the total exposure time.
Tripod – is a three-legged stand for a camera, used to stabilize and elevate the camera.
Vignetting – refers to a reduction in image brightness in the image periphery compared to the image center.

more to comeâ€¦.

Tags: photo, photography, glossary, terms

Glossary of Digital Photography Terms – Part 1

lau — Sat, 20 Jan 2007 23:45:20 +0000

Aperture of the lens – adjustment of the “iris”, which controls the amount of light entering the lens.
Auto-focus – the selection of a point in the imaging frame upon which the auto-focus system will attempt to focus.
Depth of field (DOF) – is the distance in front of and beyond the subject that appears to be in focus.
Film speed – is the measure of a photographic film’s sensitivity to light.
Image noise or Film grain – is a random, usually unwanted, fluctuation of pixel values in an image.
ISO – on film cameras it’s an indicator of the selected film speed on film cameras, on digital cameras it’s an indication of the imaging chip’s light sensitivity.
Motion blur – is the apparent streaking of rapidly moving objects in a still image.
Shutter speed – adjustment of the speed of the shutter to control the amount of time during which the imaging medium is exposed to light per each exposure.
Photography – is the process of making pictures by means of the action of capturing light on a film.
White balance – electronic compensation for the color temperature associated with a given set of lighting conditions, ensuring that white light is registered as such on the imaging chip and therefore that the colors in the frame will appear natural.

more to come….

Tags: photo, photography, glossary, terms