Rokinon 300M-MFT-BK 300mm F6.3 Mirror Lens - Micro Four Thirds

The Rokinon 300M-MFT-BK is a catadioptric (mirror) lens that packs 300mm of focal length into a remarkably small and lightweight package. On Micro Four Thirds cameras from Olympus and Panasonic, the 2x crop factor yields an effective 600mm field of view, making it a compelling option for wildlife observation, bird photography, and other scenarios where extreme telephoto reach is needed without carrying heavy glass. The mirror optical design folds the light path using reflective elements, which is what allows this lens to be so much smaller than a conventional 300mm refractive telephoto.

With 9 optical elements arranged in 9 groups, this lens is engineered to deliver sharp images with minimal chromatic aberration — a strength of mirror lens designs. The fixed f/6.3 aperture means you will need good ambient light or higher ISO settings to maintain fast shutter speeds, and the fully manual focus requires patience and practice, particularly with moving subjects. That said, for photographers willing to work within these constraints, the Rokinon 300mm mirror lens opens up a world of telephoto possibilities at a fraction of the cost and weight of traditional alternatives.