NSL Photography's™ Glossary of Photographic Terms - L

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Latent Image
The invisible image left by the action of light on photographic film, or paper. The light changes the photosensitive salts to varying degrees depending on the amount of light striking them. When processed, this latent image will become a visible image either in reversed tones (as in a negative) or in positive tones (as in a color slide).

LCD panel (Liquid Crystal Display)
A liquid crystal display (LCD) is an electronically-modulated optical device shaped into a thin, flat panel made up of any number of color or monochrome pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power. It is capable of displaying text and graphics.

Low dispersion glass, or UD (ultra low dispersion) or SD (Super Low dispersion), refers to optically superior glass, intended to minimize the chromatic aberration of the lens

One or more pieces of optical glass or similar material designed to collect and focus rays of light to form a sharp image on the film, sensor, paper, or projection screen.

Lens Aberration
Optical flaws which are present in small amounts in all photographic lenses, made up of chromatic aberration, spherical aberration, curvature of field, distortion, etc. A perfect lens would show the image of a point as a point and a straight line as a straight line, but in practice, lenses are never perfect. They reproduce a point as a patch and a straight line as a more or less curved band. Most of the trouble caused by aberrations, are inherent in the lens construction.

Lens Flare
Lens flare is the light scattered in lens systems through generally unwanted image formation mechanisms, such as internal reflection and scattering from material inhomogeneities in the lens. These mechanisms differ from the intended image formation mechanism that depends on refraction of the image rays. In good quality lenses and most images, flare is a secondary effect, widely distributed across the image and not visible, but when an image includes a very bright light source, a flare generated by a bright image region can have enough intensity to become very visible. The light produced by flares superimposes broadly across the image, adding light to dark image regions and reducing image contrast.

Lens Shade
A collar or hood at the front of a lens that keeps unwanted light from striking the lens and causing image flare. May be attached or detachable, and should be sized to the particular lens to avoid vignetting.

Lens Speed
The largest lens opening (smallest f-number) at which a lens can be set. A fast lens transmits more light and has a larger opening than a slow lens. It is determined by the maximum aperture of the lens in relation to its focal length. The "speed" of a lens is relative. For example, a 400 mm lens with a maximum aperture of f/3.5 is considered extremely fast, while a 28mm f/3.5 lens is thought to be relatively slow.

Li-Ion (Lithium Ion)
Lithium Ion batteries use lithium ions which move from the anode to the cathode during discharge and in reverse, from the cathode to the anode, when charging. Lithium ion batteries are common in consumer electronics. They are one of the most popular types of battery for portable electronics, with one of the best energy-to-weight ratios, no memory effect, and a slow loss of charge when not in use.

Light Meter
(See Exposure meter)

Lighting Ratio
The ratio of the brightness of light falling on the subject from the main (key) light and other (fill) lights. A ratio of about 3:1 is normal for color photography, and greater ratios may be used for effect in black & white work.

Limiting Aperture
The actual size of the aperture formed by the iris diaphragm at any setting. It determines, but usually differs from, the effective aperture.

Live View
Live view on a digital SLR (DSLR) camera lets you preview the photo you're about to take using the large LCD on the back of the camera, frame and focus the camera, to make a photograph. Live view is great option for photographers who can't frame an image with the traditional viewfinder due to site circumstances, and for macro photography in particular. The continuous image displayed on the LCD during live view mode, can help ensure the photographer is getting the composition right, when the use of the traditional view finder is unavailable.

Lens of relatively long focal length designed to provide a narrower angle of view than the normal or standard lens, which generally have an angle of view, expressed on the diagonal of the film or sensor format, of about 45 degrees The long focus lens thus takes in less of the view in front of it but on an enlarged scale.

The measurable amount of light which is emitted by or reflected from a source.

A measurement of brightness usually denoted in Lumens.

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