Best lenses for the 16-MPix Pentax K-5 II and K-5 IIs: Measurement data now available onlineBy Kevin Carter - Thursday January 30 2014 Lens Recommendations
Sigma also does well with the 17-50mm (26-77mm equivalent) f2.8 EX DC HSM in the zoom category. It’s also well corrected and has high peak sharpness when stopped down.
Full aperture performance isn’t bad either, but it’s better at the longer end. In second place is the moderate speed Pentax smc DA 16-45mm (25-69mm equivalent) f4 ED AL a good all round performer with a useable maximum aperture. This is followed very closely by the Pentax smc DA 16-50mm (25-77mm equivalent) f2.8 ED AL (IF) SDM in third place, but sharpness at the initial aperture is somewhat disappointing at the longer end even on the K-5 IIs.