Sigma patent filings for a Sigma 400-800mm f/8 and Sigma 180-800mm f/5.8-8.4 were found and you can read them below:
overview
- [Publication number] P2025085984
- [Release date] 2025-06-06
- [Name of invention] Telephoto zoom lens
- [Application date] 2023-11-27
- [Applicant]
[Identification number] 000131326
[Name or company name] Sigma Corporation - To provide a telephoto zoom lens that reduces the overall length and weight of the entire lens system and has little aberration variation over the entire shooting range.
- [Background Art]
[0002]
Telephoto lenses are generally designed to have a short overall length compared to the focal length by adopting a so-called telephoto type power arrangement with a positive front group and a negative rear group. In addition, since the diameter of the front group of a telephoto lens is determined by the entrance pupil diameter of the entire system, if the focal length is designed to be long to obtain a desired angle of view, the diameter of the front group becomes large and the weight becomes heavy. Since the diameter of the front group becomes large and the weight becomes heavy, the center of gravity of the optical system moves away from the photographer, which increases the physical burden on the photographer, especially when the lens is held horizontally. Furthermore, if this is made into a zoom lens, the overall length of the optical system becomes long in order to secure the space required for zooming, and the center of gravity of the optical system moves even further away from the photographer. - According to the present invention, it is possible to provide a telephoto zoom lens that reduces the overall length and weight of the entire lens system and has little aberration fluctuation throughout the entire shooting range.
Example 1
- Focal length: 309.00-579.00
- F-number: 4.11-4.12
- Angle of view: 7.89-4.21
- Image height: 21.63
- Total length: 480.57
- Back Focus: 34.6000
Example 2
- Focal length: 409.00-785.00
- F-number: 8.20-8.21
- Angle of view: 5.96-3.09
- Image height: 21.63
- Total length: 447.39
- Back Focus: 38.9535
Example 6
- Focal length: 185.40-785.00
- F-number: 5.76-8.39
- Angle of view: 13.15-3.09
- Image height: 21.63
- Total length: 478.85
- Back Focus: 40.1124
via asobinet
