Normal lens

As standard lenses lenses are in photography with a focal length that is about the diagonal of the capture image format corresponding to (Normal focal length). This results in regardless of the recording format computationally an angle of about 53 degrees, but in most cases the used angle is slightly smaller and is approximately in the range between 40 and 50 degrees.

Lenses with a shorter focal length ( picture angle and larger ) than standard lenses are called wide-angle lens, lenses with longer focal length ( picture angle and smaller ) than remote or telephoto lenses.

Properties

Before the mass distribution of the SLR zoom lenses were mostly sold together with a normal lens. Due to the high volume and the uncomplicated, often visually almost symmetrical structure are normal lenses, the cheapest fast lenses, usually with excellent imaging properties.

Common standard lenses for the small picture format almost always have top openings of 1:1.8 to 1:1.4 to applying for funds 1:2.8 to 1:1.9 formats. Other focal lengths that are as bright ( larger lenses required), are significantly more complex to construct and much more expensive. There are normal lenses for the small picture format with the top openings of 1:1.2 or 1:0.95 even - but only in the high price range. In the available light photography ( with difficult lighting conditions ) they are therefore used frequently.

In the present-day classification of fixed focal length lenses are normal lenses with the shortest focal length, which do not require retro-focus design in " one-eyed " SLR. Shorter focal lengths require additional lenses in these cameras to create behind the lens enough space for the oscillating mirror, which increases the cost of design and manufacture.

Recording Formats

With SLR cameras for the small picture format to a focal length of 50 mm has prevailed in practice, although the diagonal of the recording format (24 mm × 36 mm ) is only 43.3 mm. Some manufacturers also referred to lenses with 55 mm to 60 mm focal length lens so than normal. Compact Film Cameras with fixed lens, however, often have shorter focal lengths between about 38 mm and 45 mm.

In medium format cameras with a recording format of 6 cm × 6 cm results corresponding to approximately 80 mm as a normal focal length. The roll film format formerly often used 6 × 9 cm with 100 mm normal focal length is now considered large format.

In large-format cameras, which of 6 cm × 9 cm to 18 cm × 24 cm image format, but also with non-metric dimensions, eg 8x10 " (inches), gives, the relationship is clear: a normal lens for the image size 6 cm × 9 cm ( screen size = 10.8 cm) with a focal length of 105 mm would be for the next larger size 9 cm × 12 cm ( diagonal = 15.0 cm ) is already more of a light wide- angle lens.

With digital cameras apply regardless of the number of pixels corresponding to the diagonal of the light-sensitive sensor surface (see form factor ). At the Four Thirds standard digital SLR, the active sensor diagonal is just under 22 mm is considered normal focal length 25 mm here. For APS -C format ( sensor diagonal about 28 mm ), the normal focal length equivalent to about 30 mm.