The tamron sp af 28 75mm f28 xr di is a small light and fast standard zoom lens that can be used comfortably as a high quality fast standard lens for silver halide and digital photography the tamron sp af 28 75mm f28 xr di lens utilises the same size reduction technology developed for the popular tamron 28 200mm amp 28 300mm super zooms it offers a constant aperture of f28 throughout the zoom range making it suitable for use in low light environments