Shinichiro Ishii

Step zoom lens camera

Eyepiece variable focal length optics

Camera-attachment lens system

Optical system of a composite camera

Variable focal length objective system has movable and fixed sub-groups that maintain first and second mutual separations in first and second variation regions

Anti-vibration lens attachment

Eyepiece optical system for telescopes has first, second and third groups independently movable along optical axis to vary focal length while fourth remains stationary

Okularoptik mit variabler Brennweite

Okularoptik mit variabler Brennweite Eyepiece with variable focal length

Okular variabler Brennweite Eyepiece variable focal length