United States Patent
US Patent 3942875: Wide aperture long focal length lens
US 3942875 ยท granted 1976-03-09
Abstract
A wide aperture long focus photographic lens having internal aberration compensation and comprising an objective which is movable for focusing and a rear lens which is stationary with respect to the film plane and has an equivalent focal length which is substantially longer than the equivalent focal length of the overall lens.
| Patent Number | 3942875 |
|---|---|
| Title | Wide aperture long focal length lens |
| Filed | 1974-05-09 |
| Granted | 1976-03-09 |
| Inventor(s) | Betensky; Ellis I. |
| Assignee | Ponder & Best, Inc. |
| Number of Claims | 6 |
Abstract
A wide aperture long focus photographic lens having internal aberration compensation and comprising an objective which is movable for focusing and a rear lens which is stationary with respect to the film plane and has an equivalent focal length which is substantially longer than the equivalent focal length of the overall lens.
Claim 1
A lens defined substantially by the following data as scaled for a 24 .times. 36mm image frame: where N.sub.d is the index of refraction, V.sub.d is the Abbe number, L1-L7 are the lens elements from the object end to the image end, R1-R14 are the surface radii of the lens elements, the axial distances are measured axially between lenssurfaces, and the last axial distance is the back focal length.
Claims
6 totalA lens defined substantially by the following data as scaled for a 24 .times. 36mm image frame: where N.sub.d is the index of refraction, V.sub.d is the Abbe number, L1-L7 are the lens elements from the object end to the image end, R1-R14 are the surface radii of the lens elements, the axial distances are measured axially between lenssurfaces, and the last axial distance is the back focal length.