Sigma is well known for its Art series lenses, but the maker’s full-frame ‘Contemporary’ or C  series lenses deserve equal recognition for offering great image quality in a smaller, lighter package. Take the Sigma 24mm F2 DG DN C lens reviewed here, for example, with a metal outer barrel and milled metal aperture and focus rings, it’s a very nicely made lens indeed. What’s more, weighing just 365g and measuring 72mm in length, the L-mount version I was sent pairs incredibly well with the tiny Sigma fp sent for testing. Inside, the lens has 13 elements arranged in 11 groups, with one fancy, fluorite-like FLD element, two SLD (Super-Low Dispersion)…