Our friends and collaborators over at DxOMark have been investigating lenses for the Pentax K-50, and have just published an article assessing which score best on this well-featured little SLR. They've looked at 28 different models, from both Pentax itself and third-party makes like Sigma and Tamron, and given recommendations for the best lens to buy in various categories. This week they've also tested the Sigma APO 50-500mm f/4.5-6.3 DG OS HSM super-telephoto zoom, and compared it to the latest, and rather more expensive Nikon AF-S Nikkor 80-400mm f/4.5-5.6G ED VR. Click the links below to read more.