Sigma's 24-70mm F2.8 DG DN is a fast and versatile zoom for Sony full-frame E-mount (as well as Leica/Sigma/Panasonic L-mount). It's well-constructed, with extensive weather-sealing, and reasonably fast to focus. Output appears nice and sharp, corner-to-corner, and aberrations/ghosting are fairly well-controlled. Take a look for yourself.

See our Sigma 24-70mm F2.8 DG DN
sample gallery