This is a Vivitar 28mm/f2.8 interchangeable macro 1.5x lens designed for Olympus cameras. It has a maximum aperture of f/2.0-8.0 and a focal length of 2.0-2.8 mm. The lens is compatible with Vivitar cameras and is suitable for macro/close-up photography. The focus type is determined by the camera it is used with.
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