.EF-Mount Lens/Full-Frame Format. .Aperture Range: f/2.8 to f/32..One Ultra-Low Dispersion Element..Super Spectra Coating..Comfortable short telephoto focal length with a short working distance. As a macro lens, first and foremost, this lens affords a life-size, 1:1 maximum magnification along with a 1' minimum focusing distance and the 100mm focal length is also well-suited for portraiture.