Patent: Tamron 300mm f/2.8, 400mm f/4, 500mm f/4

By Canon Rumors It looks like Tamron may be entering the world of fast supertelephoto lenses. Three different optical formulas have appeared in the same patent application from Tamron. Embodiment 1: 300mm F/2.8 Focal length: 304.799 mm F No.: 2.8 ω: 3.997 Image height: 21.64 mm Back focus: 70.1919 mm Lens length: 298.38 mm Embodiment 2: 400mm F/4 … → continue…

From:: Canon Rumors