Photographic Glossary-L

Lab Colour
LAB is a colour model developed by the Centre Internationale D'Éclairage (CIE). These standards are internationally accepted standards for all colormetric measurements. The Lab model, like other CIE colour models, defines colour values mathematically, in a device independent manner. Lab colour is consistent colour regardless of the device producing the colour.

 Lag Time
Probably the biggest single complaint from digital camera owners is the lag time, the delay from pressing the shutter release to the camera actually taking the shot. This delay varies between camera models, the good news being that manufacturers are addressing this issue and newer digital cameras lag time is decreasing.

Lamp
A general term used to describe the various kinds of artificial light sources used in photography.

LAN
An acronym for Local Area Network. A communication networks that's physically connected by cables and confined to a single office or a single building. It enables a group of computer to exchange files and share peripherals.

Lantern slides
Is a old term used to described transparencies.

Large format camera
Is a general term for any camera having a picture format of 4x5 inches or larger. There are four main film classifications today: APS Standard Format (35mm), Medium Format, and Large Format. Large Format basically refers to any film that is larger than 120 (MF). 4x5. 6x7, and 8x10 are the common large format films today. The advantage LF has over the other films is the possibility of extreme enlargements with very little loss in quality. Contact Prints Can be made from LF negatives with out the need for a large format enlarger. Grain is non existent on large format negatives as well.

Lasso
Image editing tool used to select areas of an image for moving or cropping.

Latent image
An image formed by the changes to the silver halide grains in photographic emulsion on exposure to light. The image is not visible until chemical development takes place. 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).

Lateral reversal
A mirror image, as seen in the viewfinders of some cameras where the scene appears flipped from left to right.

Latitude
Is the degree by which exposure can be varied and still produce an acceptable image. The degree of latitude varies by film type. Faster films tend to have greater latitude than slower films. There are a few films on the market today who are claiming a very wide latitude of exposure with little loss of quality. What these film companies are bragging about is the ability to have an Exposure Index of anything from 100 to 1000 on the same roll of film depending on the lighting situation for each individual frame. Films such as Gold Max from Kodak are becoming popular among those who want a general purpose film without having to worry about what their lighting changes will be. The sacrifice is slight color differences between reality and the final print and grain size.

LCD panel ( Liquid Crystal Display. )
An electronically generated text, numeric & symbols. Before the popularity of the LCD, LED is the most common method. LCD consume only one fifth (1/5) of the power of the LED and thus have a wider application in photographic line. The only problem is, it'll turn dark at very high temperature (will resume to normal when cool down) and it will fades in extended time. (the Nikon F3 first used LCD display in 1980, I heard none is complaining about this after 17 years, did you ?) Used most commonly on cameras that shows such information as remaining exposures, flash status and aspect ratio selected.

LCD Screen
Liquid Crystal Display screen found on many digital cameras that allows previewing or reviewing of images. The screen also serves as a monitor for the interface of some camera controls. Different types exist: TFT (Thin Film Transistor) and DSTN (Double Super Twisted Nemantic) are the most common. The TFT screen is brighter and has superior colour and contrast to the DSTN. However, TFT consumes more electricity than DSTN.

LD
Low dispersion glass, or UD (ultra low dispersion) or SD (Super Low dispersion), please refer to "ED", basically, refers to optically superior glass - price too! Dispersion sometimes also refer as "colour fringing".

Leader (Film Leader).
Part of film attached to camera take-up spool. 35 mm film usually has a leader of the shape originally designed for bottom-loading Leica cameras, although most cameras simply need a short taper.

Leading
Vertical spacing between lines of type, measured in points.

Leaf Shutter
Lenses are available which have the shutter mechanism internal are referred to as Leaf Shutter lenses. The advantage of a leaf shutter over a Focal Plane Shutter is that a leaf shutter can Synch to flash lighting at any shutter speed. One disadvantage to the leaf shutter system is the maximum shutter speed is usually limited to 1/ 500 th to 1/ 1000 th of a second. A camera mechanism that admits light to expose film by opening and shutting a circle of overlapping metal leaves.

LED
Light Emitting Diode. Light producing transistors used to display dots, numeric and text in the viewfinder, slowly replacing by LCD display.

Legacy files
Files created in an earlier version of an application that may not include support, or may include less support for some features (e.g., CMS) of the newer version of the application.

Legal-size
Common name for paper measuring 8.5" by 14". Commonly used for legal or important documents.

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 is caused by aberrations, inherent in the lens construction; it's the job of the lens designer to control most of the aberrations as much as possible by combining a number of single lenses in such a way that the aberrations of one lens tend to be cancelled out by opposing aberrations in the others.

Lens aperture (f/)
The physical opening of a lens. The smaller the f/number the more light passes through.

Lens barrel
A metal or plastic tube with a blackened inner surface, in which the lens elements and mechanical components of the lens are mounted.

Lens cap
Is a plastic, rubber or metal cover which fits over the front or back of the lens to protect it.

Lens coating
A layer or multiple layers of thin anti-reflective materials applied to the surface of the lens elements to reduce light reflection and increase the amount of transmitted light.

Lens hood
A short conical shaped tube that attaches to the front of a lens to shield it from extraneous light. Helps prevent lens flare, ghost images and loss of contrast. An inexpensive must have accessory for your camera system.

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. A shield made of thin metal or rubber that fits around a lens to prevent light from hitting the front of the lens and causing flare. Also called a lens hood.

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. Determined by the maximum aperture of the lens in relation to its focal length; the "speed" of a lens is relative: 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.

Lens
A optical device made of glass or other transparent material that forms images by bending and focusing rays of light. A lens made of a single piece of glass cannot produce very sharp or exact images, so camera lenses are made up of a number of glass "elements" that cancel out each other's weakness and work together to give a sharp true image. The size, curvature and positioning of the elements determine the focal length and angle of view of a lens. Normal Lens: Any lens that produces an image in the view finder that is the same as what the eye sees is known as an a normal lens. Prime Lens: A fixed lens, 80mm, 105mm, or 200mm lens for example, are considered prime lenses. Primes are often considered faster than zoom lenses because there are fewer elements inside thus a wider aperture is possible. Prime lenses often produce a higher quality image than a zoom as well. Wide Angle Lens: Any lens that includes more in the viewfinder than a normal lens is wide angle. Wide angle lenses often have a very high depth of field and can yield very interesting perspective shots. Zoom Lens: These lenses are becoming very popular with the average person with a camera because rather than needing to carry 3 or 4 lenses which all carry a high price tag a user can have only one lens and one price tag. Of course, with the lower cost comes slightly lower quality and often times are slower lenses than the equivalent prime 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, paper, or projection screen.

Lens-Shutter Camera
A camera with the shutter built into the lens; the viewfinder and picture-taking lens are separate.

Letter-size
Common name for paper measuring 8.5" by 11". The most common printing size.

Light box
A box of fluorescent tubes balanced for white light and covered with translucent glass or plastic. Used for viewing, registering or correcting prints , film negatives and positives.

Light meter
Is an alternate term for exposure meter. Virtually all cameras on the market today have a built in light meter. This meter is used to gauge the amount of light present to determine the proper aperture and shutter speed for a given frame. Hand held meters are also available to use in addition to the camera's meter. The hand held meters offer more features and greater accuracy. Meters that gather light reflected by the subject like the on camera meters or Spot Meter are known as reflected meters. Incident meters are placed at the location of the subject and measure the amount of light falling on the object.

Light sources
A general term applied to any source of light used in photography.

Lighting Ratio
Studio Strobes or flashes are often placed to one side of the subject to prevent flat even lighting. The Lighting Ratio is the ratio of the light from one side of the subject to the other. Light fall off and shadows cause one side to be illuminated more than another. A pleasant lighting ratio will have the darker side about 1 to 1.5 stops darker than the bright side.

Lighting ratio
The ratio between the key and fill lights.

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 colour photography, greater ratios may be used for effect in black-and-white work.

Light-tight
Refers to any room or containers that is absolutely dark inside, allowing no unwanted light to penetrate.

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

Line art copy
Images containing only black and white pixels. Line art may also include one-colour image, such as mechanical blue prints or drawings.

Linear CCD
Scanner-type CCD, these sensors are long and thin, and capture an image by recording a vast number of individual "exposures" while scanning across the picture frame. These are best suited for still subjects and continuous illumination.

Linear Scanner
A scanning device that uses a linear array CCD. The linear array "sees" one line of the image at a time, and the linear array is moved past the image or the image is moved past the linear array in steps in order to capture the entire image area

Linearity
The degree to which the input of a signal is proportional to the output.

Lith film
Very high contrast film, which gives pure blacks and whites and no grays. Lith paper is a very high contrast paper, though it does normally give some grays with all but the most contrasty negatives.

Lithium ion batteries
Some of the newer digital cameras are now coming with a lithium rechargeable battery pack. Lithium batteries are lighter and more costly than NiMH or NiCd type of rechargeable cells and can be rapidly charted.

Lithograph
These films are sensitive primarily to blue wave lengths and can safely be handled in red or amber safe lights. Use is primarily in the graphic arts field because of its very high contrast.

Log e
Is the logarithmic value ( to the base 10 ) of the relative brightness exposed on the film when undergoing sensitometric testing.

Long-focus
Lens of relatively long focal length designed to provide a narrower angle of view than the normal or standard lens, which generally has an angle of view, expressed on the diagonal of the film 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.

Look Up Table
see LUT

Losslesscompression
A method of image compression where there is no loss in quality when the image is uncompressed. The uncompressed image is mathematically identical to its original. Lossless compression is usually lower in compression radio than lossy compression.

Lossy compression
A method of image compression where some image quality is sacrificed in exchange for higher compression ratios. The amount of quality degradation depends on the compression algorithm used and a user selected quality variable.

Low key
A dark image that is intentionally lacking in highlight detail.

LPI
Lines Per Inch. A measure of resolution, usually screen frequency in halftone.

Luminance
Lightness. The highest of the individual RGB values plus the lowest of the individual RGB values, divided by two; a component of Hue-Saturation- Lightness image.

Luminosity
The brightness of either a light source or a reflective surface.

Lut
Look-up table. The table of colours a computer can display at a given time. The computer uses the table to approximate the desired colour from the range it has available.

Lux
A measurement of the light intensity. One Lux in video means light level of a candle light. l Lux approximately equals to 10 footcandles (1 Lux = 10.764 fc).