Lenses

Lenses are characterized by two fundamental specifications, f-stop and focal length. The f-stop is a number which specifies the aperture versus focal length ratio of the lens. It is also known as the lens ‘speed’ as it indicates how much light can pass through the lens. The lower the number, the greater the light throughput (and the smaller the depth of field/focus).

 

The focal length can be used to calculate the ratio between image size and throw distance. To do this, the actual size of the image-producing element (e.g. the LCD panel) has to be known and the relationship is as follows.

Ratio between image size and throw distance

       Fig 43

Most projectors come standard with a zoom lens, i.e. a lens with a variable focal length. Specification can be the zoom range in the focal length, e.g. 60-105mm, or expressed as a zoom ratio, e.g. 1.3x, which indicates the ratio between the longest and shortest focal length.

 

There is no clear standard for specifying lenses on projectors. Some manufacturers specify throw ratio, some focal length, some zoom ratio, and some use a chart showing minimum and maximum throw distances in relation to image sizes. It can be confusing – so read the data with care!


< DLP

 

dnp denmark is the worldwide large-screen centre of Dai Nippon Printing Co. Ltd. With a 65 % market share, dnp is the world’s leading supplier of optical projection screens for high quality display solutions.

The dnp optical screen portfolio includes an extensive range of optical projection screens for both front and rear projection screen applications for all environments including home cinema / home theatre, meeting rooms / conference rooms, control rooms, signage & advertising and more.

dnp denmark as
Skruegangen 2
DK-2690 Karlslunde
Tel.: +45 46 16 51 00
Fax: +45 46 16 52 00
E-mail: dnp@dnp.dk
See worldwide dnp contacts
Home / About dnp / Technology / Products / Download / dnp TV / Contact / For Partners / Sitemap Introduction in various languages:
   Copyright dnp denmark as © 2016