Optical apparatus for changing focus and focal length
AssigneeEastman Kodak Company
InventorPeter Labaziewicz
Life of this patent
Estimating the term…
Abstract
Optical apparatus having first and second lens groups moveable along an optical axis, and a cam and follower mechanism for communicating relative axial displacement to the second lens group in response to axial movement of the first lens group for changing the focal length of the optical system. The cam and follower mechanism is characterized by a plurality of cam steps each having first or dwell surfaces for maintaining the relative axial displacement constant in response to axial movement of the first lens group, to accommodate focusing between at least two focus positions at a fixed focal length, and second or ramp surfaces for changing the relative axial displacement in response to axial movement of the first lens group, for changing the focal length of the apparatus.
Claims9
Apparatus having first and second lens groups moveable along an optical axis, and a cam and follower mechanism for communicating relative axial displacement to said second lens group in response to axial movement of said first lens group for changing the focal length of the optical system;
- characterized in that:
- said cam and follower mechanism includes a plurality of cam steps each having first means for maintaining said relative axial displacement constant in response to axial movement of said first lens group, and second means for changing said relative axial displacement in response to axial movement of said first lens group.
Apparatus for varying a focal length of a zoom lens system having first and second lens groups moveable along an optical axis, said apparatus comprising cam means for communicating motion to said first and second lens groups and cam follower means coupled with said first and second lens groups for engaging said cam means;
- characterized in that:
- said cam means includes a plurality of cam surfaces arranged in a stepwise fashion connected by slant surfaces, each of said cam surfaces defining a discrete focal length for the zoom lens system, said focal lengths ranging from relatively long to relatively short focal lengths, said cam surfaces maintaining a relative axial displacement of said first and second lens groups constant in response to axial movement of said first lens group;
- and
- said apparatus includes means for moving one of said lens groups to cause said cam follower means to engage a selected one of said plurality of cam surfaces to fix the focal length of the zoom lens system at one of said discrete focal lengths.
Dependencies are inferred from the claim text.