Bobby Tonelli reviews the Tamron 70-300mm f/4.5-6.3 Di III RXD, the lightest telephoto zoom for Sony E-mount at 545 grams: weather resistant, 67mm filter thread, autofocus on a par with Sony's lenses and an aperture reaching f/6.3 by 250mm. Singapore samples show sharp centres with slight edge softness at 300mm.
