Diagonal angle of view 32deg 1139 8deg 1539 lens construction elementsgroups 139 no of diaphragm blades 7 minimum aperture 32 45 closest focusing distance m 15 maximum magnification x 025 at 300mm filter diameter mm 58 the optical system construction and exterior are the same as the ef 75 300 mm f4 56 iii usmrsquo the difference is that it uses a dc motor instead of a usm to drive the af this lens has the same optical system construct