Objective has a focal length is variable and optical system relates to such objectives for the production of films special effects

摘要

Objective has variable focal intended for equipping the trucas and of the benches - securities for the production of special effects on the films. / p & & p & the objective is constituted by four groups of lenses: a first group converging portion 10 of four lenses, a second group diverging portion 20 of four lenses, a third group of six converging lens 30, a convergent 40 fourth group of two lenses, all of these groups having a formula determined, and the first 10 and the third group 30 being fixed and mobile. / p & & p & the fact of equipping the trucas or banks - respects, this makes it possible to remove completely the set of parts mechanical, incorporated in the differences of sharpness of the image, and simplifies the manufacturing considerably.