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We've heard in the past that Sigma is working on super telephoto lenses, namely a 500mm f/4 OS. Now a patent has appeared for a 400mm f/2.8 OS lens from Sigma. I think the biggest challenge for Sigma in this area is going to be autofocus. Super telephoto lenses are the least forgiving when it comes to focus accuracy in most situations.
Patent Publication No. 2015-64436 (Google Translated)
- 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)
Source: [EG]
