Sigma was a brand long associated with budget-conscious third-party lens options for DSLR owners. No longer. The company has launched into the world of luxury lenses with its Art series – a selection of fast, professional-grade prime models.

We tested the Sigma 50mm f/1.4 DG HSM Art Lens over the course of two weeks to see if at around $970 the camera represented bang for your buck.The Canon equivalent is around $1000 dollars dearer.

Now, paying almost a grand for a 50mm lens may seem quite a lot, but there are a huge number of reasons to consider a fast prime lens in your kit if you don't already have one – especially so if you have a full-frame camera.

The uses of a standard 50mm focal length, which closely mimics the human eye's field of view, are numerous. It's the best starting point if you want to experiment with a prime lens. Common wisdom is that using prime lenses is also a great way to improve your composition skills, because you have to follow the well-established doctrine of 'zooming with your feet' – getting closer to your subject rather than sitting back lazily with a zoom lens.

The other reasons primes are often so useful is that they are probably quite fast, and provide better image quality because they don't have to make optical sacrifices like a zoom. Consider this, even the professional grade zooms for the likes of Sony, Nikon and Canon usually can only shoot at an aperture of F2.8 or even F4. It's a lot easier for a prime lens to be manufactured to shoot at F1.4 without losing information.

The first thing you notice about the Sigma is its heft. This is a heavy lens, coming in at 815 grams – more than 200 grams more than Canon's 1.2L.

The size and weight are the biggest downsides to this lens. Expect to get a sore shoulder after a half-day shooting. Yet the weight displacement works well on larger, full-frame format digital bodies such as a Nikon D810 or Canon 5D IV. If you are shooting on a smaller camera, I'd recommend a smaller prime lens simply because the weight displacement would be very awkward. Our test copy was mounted on a Canon 5D Mk III and suited the camera perfectly.

The autofocus was pretty silent, although not as quiet as a Canon 50 1.2L to which I compared this unit directly. It also seemed a little slower in low-light situations than the Canon, but not critically so. On the plus side, it was noticeably sharper at wider apertures, and to my eyes produced better, smoother bokeh – the out of focus parts of the image. This is a great option for weddings, portraiture and commercial studio work. Size and weight make it a poorer choice for street photography or photojournalism.

Not only has Sigma put image quality normally out of reach of everyday consumers and enthusiasts into a relatively affordable package, it has produced a lens that in some respects outperforms the competition.