Fast ultra-wide angle lens system
AssigneesAsahi Kogaku Kogyo Kabushiki Kaisha, Asahi Seimitsu Kabushiki Kaisha
InventorsTakayuki Ito, Yasuyuki Sugano
Life of this patent
Estimating the term…
Abstract
A fast ultra-wide angle lens system is provided which includes a front lens group having a negative power, a diaphragm, and a rear lens group having a positive power, arranged in this order from a side of an object to be photographed. The lens system satisfies the following conditions: -0.5<f/f.sub.F <-0.2; (1) 7.0<.SIGMA.d.sub.F+S /f<12.0; and (2) 5.0<.SIGMA.d.sub.R /f<10.0, (3) wherein f represents a focal length of the entire lens system, f.sub.F represents a focal length of the front lens group, .SIGMA.d.sub.F+S represents a sum of the length of the front lens group and a distance between the front lens group and the rear lens group, and .SIGMA.d.sub.R represents a length of the rear lens group.
Claims4
An ultra-wide angle lens system comprising:
- a front lens group having a negative power, a diaphragm, and a rear lens group having a positive power, arranged in this order from an object side of the lens system, in which the following conditions are satisfied:
- -0.5<f/f.sub.F <-0.2 (1)
- 7.0<.SIGMA.d.sub.F+S /f<12.0 (2)
- 5.0<.SIGMA.d.sub.R /f<10.0 (3)
- wherein,
- f represents a focal length of the entire lens system,
- f.sub.F represents a focal length of the front lens group,
- .SIGMA.d.sub.F+S represents a sum of the length of the front lens group and the distance between the front lens group and the rear lens group;
- and,
- .SIGMA.d.sub.R represents a length of the rear lens group.
Dependencies are inferred from the claim text.