Jason Kim Portal

Aberration.

The inability of your lens to generate a legitimate graphic, particularly at the edge of your photograph.
Usually, the additional costly the lens, the far better its optical quality and also the fewer aberrations.

The region of your scene that a lens can cover. The focal length in the lens determines the angle of watch. A wide-angle (short-focal-length) lens involves additional of your scene than a regular (normal-focal-length) lens or telephoto (long-focal-length) lens. Position of watch is basically the angle at which lumination rays can pass via the lens to generate an graphic on the film.

Aperture

The aperture will be the opening formed through the blades in the iris or diaphragm in the lens, via which lumination passes to expose the film. Aperture size is typically provided in f-numbers, the bigger the amount, the smaller the opening. Aperture size with each other with shutter speed ascertain the amount of lumination falling on the film (exposure). The aperture is occasionally known as the “stop”.

Aspherical lens

A lens with a curved, non-spherical surface. Used to cut down aberrations and accomplish a additional compact lens size. Having a spherical lens, rays travelling from your lens periphery produce the graphic before the perfect focal place and give a blurred graphic centre. With an aspherical lens, even the rays travelling from your lens periphery converge at the perfect focal place, therefore creating a sharp graphic.

Chromatic aberration

The inability of your lens to bring all lumination wavelengths (particularly red & blue) into the same plane of focus, therefore causing overall blur. Usually found in normal large-aperture telephoto and super-telephoto lenses. Not improved by reducing aperture size. Can be corrected with low dispersion (ED, LD SD) glass.

Colour temperature

A method of expressing the colour content and quality of lumination and measured in Kelvin (K). “Photographic daylight” has a colour temperature of about 5500K. Photographic tungsten lights have colour temperatures of 3200K to 3400K depending on their construction.

Depth of Field

The distance between the nearest and furthest objects in a photograph that are considered to be acceptably sharp. Dependant on aperture, focal length and focused distance. The smaller the aperture, the wider the lens and also the further the focused distance, giving a higher depth of field and vice versa.

Electronic flash

Designed to provide lumination where the lighting on the scene is insufficient. Electronic flash requires substantial voltage, typically obtained via batteries and a voltage-multiplying circuit which discharge a brief, intensive burst. Commonly considered to have the same photographic effect as daylight. Modern flash units have multiple TTL exposure control functions and auto focus control.

F-numbers or F-stops

Numbers on the lens aperture ring and also the camera’s LCD (where applicable) that indicate the size of lens aperture. The lower the amount the bigger the aperture. Because the scale rises, each amount is multiplied by a factor of 1.4. Standard numbers are 1.0,1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc., each change resulting in a doubling or halving in the amount of lumination transmitted through the lens to the film.

Film Speed

ISO stands for International Standards Organization and numbers such as ISO 100 or ISO 400 etc. give the sensitivity of film to lumination. The higher the amount, the additional sensitive or faster the film. Essentially, the slower the film (low ISO No.) the sharper and clearer the photograph. Grainy effects can be achieved with fast films (substantial ISO No.).

Flash sync speed

Exposure time with a focal-plane shutter is measured from your moment the first curtain is released until the moment the second curtain is released. The instant the first curtain closes, the electrical contacts for X sync close and instantly fire the flash.

Focal Duration

The distance from your film to the optical centre in the lens when the lens is focused on infinity. Focal length on most adjustable video camera lense is marked in millimetres on the lens mount. On 35mm-format cameras, lenses with a focal length of 50mm are known as typical or regular lenses. Lenses of 35mm or less are known as broad angle lenses and lenses of 85mm or additional are known as telephoto lenses. Lenses which allow varying focal lengths without changing focus are known as zoom lenses.

Lens

One or additional pieces of optical glass or similar material designed to collect and transfer rays of lumination to form a sharp graphic on film, paper or a projection screen. In practical photography, compound lenses made of your amount of elements of different types of glass are employed. This enables the manufacturer to correct most in the faults (aberrations) found in simple lenses and provide images that are sharp across the whole picture.

Lens Speed

The largest aperture(smallest F-stop) at which a lens can be set. Fast lenses transmit additional lumination and have bigger openings than slow lenses. Determined through the maximum aperture in relation to focal length. Lens speed 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 considered to be quite slow.

Perspective

Perspective is a two-dimensional representation of your three-dimensional scene. In photography this can be achieved by viewing 3-D objects from an angle rather than head-on. A photograph is also provided perspective if there are objects in the foreground, middle distance and background, giving the whole scene “depth”.

Single-Lens-Reflex (SLR) Camera

Lighting entering the camera via the lens is reflected up by a mirror behind the lens onto a ground glass screen above. This screen is viewed via the viewfinder and a glass pentaprism which turns the graphic the correct way up. Other camera functions such as lumination metering and flash control also operate via the camera lens.

Zoom Lens

A lens which can be adjusted to a broad range of focal lengths without a change in focus, therefore an alternative for a amount of individual lenses of various focal lengths. A difficult type of lens to design and manufacture, but very useful for the photographer who likes to travel lumination.

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