I could not believe my eyes when I read the specifications of the Sigma 24-35mm f/2.0 DG HSM Art lens.

Consider this: One Canon EF 35mm f/2.0 IS USM prime lens will set you back by $1,199.

With this lens - the world's first zoom lens with a constant f/2.0 maximum aperture - you are essentially getting a trio of 24mm, 28mm and 35mm f/2.0 prime lens for only $1,488. That's not to mention the other focal lengths you get within its zoom range.

This lens is good for photographers who work in dim lighting conditions, as it allows more light to enter the image sensor while keeping the shutter speed fast enough to keep the image sharp.

Such a large aperture also lets photographers achieve excellent bokeh effect - the deliberately blurred out-of-focus areas in an image.

The lens can be used with both full-frame and APS-C DSLRs, as well as with film SLRs. The lens is available in Singapore for Canon, Nikon and Sigma DSLRs.

In this review, I used the Canon version, with a Canon EOS 7D (APS-C) and Canon 6D (full-frame).

With its metallic frame and textured rubber control rings, this solidly built lens exudes a premium quality feel.

The focus and zoom rings are both smooth and easy to turn.

It is not exactly lightweight at almost 1kg, but you would expect the heft, given the amount of glass needed for such a large aperture.

Its autofocusing capability is on a par with both my Canon 16-35mm f/2.8 L USM and Canon 24-105mm f/4 L lenses.

Though not as silent as the Canon lenses, it is still quiet enough for solemn events.

The image quality I got from this lens is superb. On a full-frame DSLR, images are only slightly soft at the edges compared to the centre when shooting at f/2.0.

Sharpness becomes constant throughout the frame when the

aperture is stepped down to f/5.6.

I found that images look sharper, especially at the corners, at f/2.0 when the lens is paired with an APS-C DSLR compared to a full-frame DSLR.

Chromatic aberrations are very well controlled. There was hardly any purple fringing throughout the whole zoom range and with different aperture sizes, using both APS-C and full-frame DSLRs.

As you might expect from a large-aperture lens, you get slight vignetting - the darkening of the corners of an image - with images shot at f/2.0. I found this to be less of an issue when the aperture is stepped down to f/5.6 or f/8.0.

Vignetting is also less prominent when the lens is used with an APS-C DSLR, compared to a full-frame DSLR. My guess is that the vignetting artefact is naturally "cropped" out through use of the smaller APS-C sensor.

The only downside is the lack of a built-in image stabiliser in the lens.

That said, the large aperture likely makes this a non-issue in most cases.

Verdict: Delivering prime lens quality in a zoom lens and at an extremely affordable price, this should be on the shortlist of photographers looking for prime lenses for their DSLRs.