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Sigma 18-50mm f/2.8 DC DN Contemporary:
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A Sigma 50-135mm F2.8 DC DN patent was found by asobinet and while most patents do not become lenses this could be a useful 3rd party 70-200mm full frame equivalent lens to compliment the popular Sigma 18-50mm f/2.8 DC DN Contemporary.

overview

• [Publication number] P2023179307
• [Release date] 2023-12-19
• [Name of the invention] Imaging optical system
• [Application date] 2022-06-07
• [Applicant]
  [Identification number] 000131326
  [Name or name] Sigma Co., Ltd.
• An object of the present invention is to provide an imaging optical system that is equipped with an image stabilization mechanism, has a small open F value over the entire zoom range, and has achieved miniaturization.
• [Background technology]
  【0002】
  In recent years, so-called mirrorless cameras have become popular, which do not include a quick return mirror that is placed between an imaging optical system and an image sensor and guides light to a finder optical system.
• 【0003】
  Mirrorless cameras have smaller casings due to the elimination of mirrors, and as a result, there is a need for smaller imaging optical systems. Additionally, there is a demand for a large-diameter zoom lens that is equipped with an image stabilization mechanism and has a small aperture F value over the entire zoom range.
• 【0005】
  Patent Document 1 discloses a positive lead type zoom lens that has a bright open F value of about 2.8 and in which the lens group closest to the object side is fixed to the image plane during zooming. The zoom lens disclosed in Patent Document 1 has the advantage of high convenience and robustness because the total optical length does not change, but there is a problem that the size of the imaging optical system is large.
• 【0006】
  Patent Document 2 discloses a positive lead type zoom lens that has a bright open F value of about 2.8 and has a shortened overall optical length at the wide-angle end. In the zoom lens disclosed in Patent Document 2, many lens groups with large diameters that move during zooming are arranged on the image side of the aperture stop, so the mechanism required for zooming becomes large and the lens barrel is There is a problem that the size in the radial direction is large.
• 【0007】
  The present invention has been made in view of these circumstances, and it is an object of the present invention to provide an imaging optical system that is equipped with an image stabilization mechanism, has a small open F value over the entire zoom range, and is miniaturized.

Example 1

• Focal length: 51.50-132.00
• F value: 2.92
• Angle of view: 31.56-12.01
• Image height: 14.20
• Total length: 130.00-154.13

via asobinet