Lens review

Sigma 50-150 mm f/2.8 APO EX DC HSM

3. Build quality

The 50-150 mm lens is a member of EX (Excelence) family - the highest series sold by Sigma. No wonder it is made of high quality materials. It looks durable thanks to metal bayonet and internal focusing system causing no change in physical length of the lens body which suggests better protection from dust.

Despite dimensions (it is significantly smaller than 70-200 f/2.8 model and comparable to many typical 70-300 mm zoom lenses) operating Sigma 50-150 mm is comfortable. It has two separate rings for manual focusing and zooming and both work very smoothly and precisely. It also has standard (non-rotating) filter thread (67 mm). On a picture below you can see Sigma compared to Canon 70-300 mm IS USM and Canon EF-S 18-55 mm.

The lens construction is rather complicated. It consists of 18 elements in 14 groups. There is "APO" inscription on the casing so we can expect Special Low Dispersion (SLD) elements inside and indeed there are four of them. We must point out that Sigma 50-150 mm has equal amount of elements to Sigma 70-200 f/2.8 Macro although it is designed for APS-C and it has no "Macro" function. All in all construction looks very good.