It looks almost identical to the Canon FD 100-300mm f5.6 lens, except for the standard red ring indicating that it belongs to this prestigious line of lenses. In this case, the lens has 1 flourite and 1 UD element to drastically reduce spectral aberrations and ensure sharpness across the frame. This lens, therefore, has one of each which does set it apart from the standard lens in the same focal range.