Sigma 150mm f/2.8 DG DN Macro Patent Found

Asobinet found a Sigma 150mm F2.8 DG DN Macro patent that is interesting for photographers that like telephoto macro.

Overview

[Publication Number] Japanese Patent Application Laid-Open No. 2021-144142 (P2021-144142A)
[Publication date] September 24, 2021
[Title of Invention] Imaging Optical System
[Application date] March 12, 2020
[Applicant]
[Identification number] 000131326
[Name or name] Sigma Co., Ltd.
PROBLEM TO BE SOLVED: To provide an imaging optical system having high optical performance in a wide range from infinity to a close region exceeding −0.5 times a photographing magnification and having a focus lens group having a small weight.
[0005] Further
, in recent years, moving image shooting using a digital still camera has become common. In movie shooting, in order to maintain the in-focus state, a method is often adopted in which the focus lens group is constantly vibrated (wobbling) in the optical axis direction and the change in contrast is constantly confirmed.
[0006] When
the weight of the focus lens group is large, it becomes difficult to drive the wobbling at high speed and with high accuracy. There is a possibility that the wobbling drive can be performed by increasing the size of the actuator, but in that case, it becomes difficult to reduce the size and weight of the photographing lens. Therefore, weight reduction of the focus lens group is required. In a floating type imaging optical system having two focus lens groups, since only one focus lens group can be used for wobbling, at least one focus lens group is required to be lightweight. There is.