The Sigma 16mm f/1.4 DC DN Contemporary is a wide-angle prime lens with a huge maximum aperture of f/1.4.

A large aperture allows more light to hit the image sensor, so photographers can use lower sensitivity settings for less image noise.

It also helps to create attractive, out-of-focus areas of the image, known as the bokeh effect.

There are two versions of this lens, to cater to Sony E-mount APS-C and Micro Four-Thirds mirrorless cameras. The lens offers focal lengths of 24mm and 32mm on an APS-C and a Micro Four-Thirds camera, respectively.

The Straits Times tested the Sony E-mount version with a Sony a7R II full-frame mirrorless camera in APS-C crop mode.

The lens uses a rounded nine-blade diaphragm for bokeh effect and has 16 glass elements in 13 groups to help reduce optical aberration.

The lens feels sturdy and exudes a premium vibe, unlike the plastic feel of some other lenses. According to Sigma, the lens is dust-and splash-proof due to a special sealing process.

It lacks an image stabilising motor, but has a stepping autofocusing (AF) motor to ensure quiet and high-speed AF performance.

However, while it is certainly quiet, it is not exactly fast.

Getting a focus lock takes about 0.5 seconds in bright sunlight and up to 2 seconds in dim lighting conditions. I also found the AF performance lacking when tracking fast-moving subjects, with a few out-of-focus shots.

However, this is one of the best lenses I have tested in terms of sharpness.

The centre of the images stayed sharp from f/1.4 to f/11 and deteriorated only at f/16. Edge-to-edge sharpness is generally good, especially when stopped down to f/5.6 and lower.

With its large aperture of f/1.4, the bokeh created by this lens really makes the subject stand out.

What is more, the bokeh is of the type which distant lights appear as orbs - great for beauty portraits.

Chromatic aberration, or purple fringing, is kept relatively low throughout the entire aperture range.

However, the best part about the lens is its price. At $648, it is a bargain. In comparison, the closest Sony E-mount lens in terms of specs - the Sonnar T*E 24mm f/1.8 ZA - costs $1,699.

• Verdict: The Sigma 16mm f/1.4 DC DN Contemporary is an excellent wide-angle prime lens that produces a sharp and pleasing bokeh effect at an affordable price.