There is a new crowdfunding project for a Redcat 250mm f/4.9 telephoto full-frame lens by William Optics on Kickstarter that already reached its financial goal (currently at $45,459 from the original $30,000 goal). The lens is described as "The world's sharpest 250mm telephoto lens ever made for full frame cameras, at Apochromatic specification." The company behind the project is William Optics, a 1996-founded manufacturer of refractor telescopes, binoculars, digital camera adapter lenses for telescopes, eyepieces, diagonals and other accessories.
See also the related posts in the Nikon D850 Facebook group.
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