Sigma is scheduled to announce Sigma 18-50mm F2.8 DC DN Contemporary lens for Leica L mount and Sony E mount soon. Now, according to the Asobinet, Sigma also spotted the patent for another new lens: Sigma 150mm f/2.8 DG DN macro Full Frame lens.
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.
When the weight of the focus lens group is large, high-speed and high-precision wobbling drive becomes difficult. 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.
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