Sigma 50-140mm F2.8 for Mirrorless APS-C Patent Found

Sigma 50-140mm f/2.8 DC DN

The patent for the Sigma 50-140mm f/2.8 APS-C mirrorless lens has been found.

This would be the first telephoto DC DN (APS-C) lens from Sigma and it would go to compete with one of Fujifilm’s best lenses, the Fujinon XF 50-140mm f/2.8 R LM OIS WR.

•  Application: Sigma Co., Ltd.
  Public number: P2023090116
  Application number: P 2021204904
  Release date: 2023-06-29
  Name of invention: Imaging optics
• [Issue] Provides a small imaging optics with a small open F value in the entire zoom range.
• Mirrorless cameras have a smaller housing due to the abolition of mirrors, so it is required to miniaturize the imaging optics accordingly. In addition, large aperture zoom lenses with small open F values are required throughout the zoom range.
• In Patent Document 1, a positive read type zoom lens with an open F value of about 2.8, which is bright and the lens group on the object side is fixed to the image surface at the time of variable doubling is disclosed. The convenience and robustness are high due to the fact that the optical total length does not change, but there is a problem that the size of the imaging optical system is large.
• In Patent Document 2, a positive read zoom lens with a bright open F value of about 2.8 and a shortened optical total length at the wide angle end is disclosed. However, there are many lenses with large diameters that move when multiplying on the image side rather than the opening aperture, so the mechanism required for the transformation is larger and the diameter size of the lens barrel is larger.
• This invention is made in light of this situation, and aims to provide a small imaging optics with a small open F value throughout the zoom range.
• Example 1 (for 50-140mm F2.8 APS-C)
  Zoom ratio 2.70
  Wide angle intermediate telephoto
  Focal length 50.50 85.38 136.50
  F number 2.92 2.92 2.92
  Total angle of view 30.62 18.00 11.40
  Statue height 14.20 14.20 14.20
  Lens total length 125.00 137.38 145.00

Fujinon XF 50-140mmF2.8 R LM OIS WR: BHphoto / AmazonUS / Adorama

via ipforce via digicame-info