Sigma 50-120mm F2.8 DC OS Contemporary

The Sigma 50-120mm F2.8 DC OS Contemporary is a telephoto zoom for APS-C mirrorless cameras with a constant F2.8 aperture. It is available for Sony E, Fujifilm X and Canon RF and covers roughly 75-180mm in 35mm terms according to Sigma. It joins the Sigma 10-18mm F2.8 DC DN and 18-50mm F2.8 DC DN to form a constant-F2.8 trio, and Sigma says all three together weigh less than 1 kg.

Optical design

Sigma specifies 18 elements in 13 groups, including one FLD, three SLD and four aspherical elements. According to Sigma, aberrations are corrected from center to edge to achieve high contrast. The 11-blade rounded diaphragm closes to F22. Minimum focusing distance is 23 cm at the wide end and 55 cm at the long end, with magnification of 1:3 and 1:4.7. The angle of view is 31.7 to 13.5 degrees on Sony E and Fujifilm X, and 30.0 to 12.8 degrees on Canon RF. The filter thread measures 55mm.

Autofocus and handling

An HLA linear motor drives the autofocus. Optical stabilization uses Sigma's OS2 algorithm, rated at 6.5 stops at the wide end and 4.5 stops at the long end under CIPA guidelines. The design aims to minimize focus breathing. Sigma removed the focus mode and OS switches for a minimal layout. According to Sigma's US press release, it is the first Contemporary APS-C zoom with an aperture ring. The release does not say how the Canon RF version handles this.

Build and size

The Sony E version weighs 390 g and measures 66.8mm by 99.0mm. The Fujifilm X version also weighs 390 g at 99.3mm length. The Canon RF version weighs 410 g with a 69.0mm diameter and 97.0mm length. The structure is dust and splash resistant, and the front element has a water and oil repellent coating. Sigma notes the lens is not waterproof.

Where it fits

On Fujifilm X, the Fujifilm XF 50-140mm F2.8 R LM OIS WR covers a longer range and the Fujifilm XF 55-200mm F3.5-4.8 R LM OIS is slower. On Sony E, the Sony E 70-350mm F4.5-6.3 G OSS and the Sony E 55-210mm F4.5-6.3 OSS reach further but are slower. On Canon RF, the Canon RF-S 55-210mm F5.0-7.1 IS STM is a much slower option.

Pros and cons

Pros

• Constant F2.8 across 50-120mm
• Optical stabilization rated up to 6.5 stops
• Compact for the class: 390 g
• Dust and splash resistant structure

Cons

• No AF/MF or OS switch on the lens
• Telephoto end of 120mm is shorter than 140mm to 210mm alternatives
• Quality claims come from Sigma, independent measurements are still needed

Verdict

A compact, stabilized F2.8 telephoto zoom that completes Sigma's APS-C trio. It suits users who want a bright, light portrait and event zoom on Sony E, Fujifilm X or Canon RF.