New patent application for Pentax 70-150mm, 100-170mm, 70-180mm, and 150-250mm lenses

3 days ago
Categories: Patents, Pentax lenses

Ricoh has a new patent application released on May 30, which includes several optical lens designs/calculations:

70-150mm f/4.6-5.7
100-170mm f/4.6-5.2
70-180mm f/4.1-6.1
150-250mm f/5.3-7.9

Additional informtion:

[Publication number] P2025083507
[Release date] 2025-05-30
[Name of invention] Zoom lens, lens barrel and imaging device
[Application date] 2025-03-14
[Show division] Division of P 2021020788
[Original application date] 2021-02-12
[Applicant]
[Identification number] 000006747
[Name or company name] Ricoh Co., Ltd.
A zoom lens, a lens barrel, and an imaging device are provided that are capable of suppressing aberration fluctuations that accompany changes in shooting distance.
[Background Art]
[0002]
Conventionally, various types of zoom lenses for digital cameras are known. In particular, as a zoom lens with an extended focal length on the telephoto side, a positive-lead zoom type is generally used, in which the positive, negative, and rear groups are arranged in order from the object side, and a small zoom lens with high optical performance is required over the entire zoom and shooting distance range. In addition, in order to realize a high-speed automatic focusing operation (autofocus), an inner focus method is known in which a lens group located inside the heavy front lens is moved to reduce the weight of the focusing lens group. In particular, a rear focus method, in which a lens group close to the image plane, which is lightweight and can easily have a small lens outer diameter, is used as the focusing lens group in recent years.
[0003]
However, in the conventional rear focus method, the change in curvature of field is large at the short focal length end, and the change in spherical aberration and coma aberration is large at the long focal length end, so that the image quality is degraded according to the change in shooting distance. In particular, lenses for high-speed AF are often composed of a small number of lenses in order to further reduce the weight of the focusing lens group, but naturally, the fewer the number of lenses, the more difficult it is to suppress the aberration fluctuation according to the shooting distance. In addition, there is a method of using a glass material with a low specific gravity to reduce the weight of the focusing lens, but since low specific gravity glass materials generally have a low refractive index, the suppression effect of the aberration fluctuation is weak.
The present invention has been made in consideration of the above
points, and has an object to provide a zoom lens, a lens barrel, and an imaging device that can suppress aberration fluctuations that occur with changes in shooting distance.
[0013]
First, the terms used in this specification are defined. In this specification, a “lens component” refers to a lens that has only two refracting surfaces, an object side surface and an image side surface, that come into contact with air in the normal optical path. For example, a single lens or a cemented lens corresponds to a “lens component”. In this specification, “anti-vibration” refers to preventing image blur caused by lens shaking during shooting, and an “anti-vibration lens” refers to a lens that is driven to prevent image blur caused by lens shaking during shooting.
[0020]
A part of the second lens group G2 (here, the first and second lenses of the six lenses) is an anti-vibration lens group that enables image blur correction by moving in a direction perpendicular to the optical axis during image blur correction.