doubler n : an electronic device that doubles the voltage or the frequency of an input signal
- One who doubles
- to double, duplicate
- A cet instant précis, il a décidé de doubler la mise.
- to double-cross
- Nous avons été doublé ce coup-ci.
- to overtake,
- Sur l'autoroute, nous avons eu l'occasion de doubler de nombreux véhicules.
- to dub
A teleconverter is a secondary lens which is mounted between the camera and a photographic lens. Its job is to enlarge the central part of an image obtained by the objective lens. For example a 2× teleconverter enlarges the central 12×18 mm part of an image to the size of 24×36 mm. Teleconverters are typically made in 1.4×, 2× and 3× models.
The use of a 2× teleconverter (or doubler) gives the effect of using lens with twice the focal length. It also decreases the intensity of the light reaching the film by the factor of 4 (an equivalent of doubling the focal ratio) as well as the resolution (by the factor of 2).
doubler in Czech: Telekonvertor
doubler in German: Telekonverter
doubler in French: Multiplicateur de focale
doubler in Luxembourgish: Telekonverter
doubler in Polish: Telekonwerter
doubler in Russian: Телеконвертер
doubler in Finnish: Polttovälin muuttaja
doubler in Swedish: Telekonverter