The af s dx micro nikkor 40mm f28g is a true 11 macro lens for dx format dslrs like the d90 d5100 and d7000 incorporating the nikkor silent wave motor swm for quiet accurate focus operation a large f28 aperture and a 163cm close focusing this lens is ideal for shooting both intimate close up details or general portraiture with flattering out of focus elements when mounted on a dx format slr the picture angle is equivalent to a focal length of about 60mm in 35mm format