Sigma 400mm f/2.8 OS Lens Patent

Egami found a patent for Sigma 400mm f/2.8 OS lens. Their 300mm f/2.8 is priced at $3,449.00, and they already have good telephoto lenses with all types of aperture sizes, so if this one turns out to be an actual product (both quality and focusing speed), the lens could be a good competitor to the big brands.

• Patent Publication No. 2015-64436
  • Published 2015.4.9
  • Filing date 2013.9.4
• Example 1
  • Focal length 390.00mm
  • Fno. 2.91
  • Total angle of view 2ω 6.29 °
  • Image height Y 21.63mm
  • Overall length of the lens 353.00mm
  • Positive, positive positive and negative negative 5-group configuration
  • Inner Focus (fourth group)
  • Anti-vibration (part of the fifth group)