This beast of a prime boasts the longest focal length in Sigma’s Art f/1.4 series, but is it a portrait photographer’s dream lens? Michael Topham finds out
Sigma 105mm f/1.4 DG HSM review: Image Quality
To get a good impression of what the lens is truly capable of and how it performs in the type of situations it’ll see regular use, it was used on a demanding contre-jour portrait shoot at the coast and at a wedding to capture a series of candid images. In the first instance our Canon-fit review sample was mounted to an EOS 5DS R and for the wedding it was paired up with the EOS 5D Mark III.
As to be expected for a fast mid telephoto prime, the fall off in focus occurs incredibly quickly at f/1.4, forcing you to be very precise with your focusing technique in order to resolve pin-sharp focus on a person’s eyes, or your subject.
As the sample images that support this review illustrate, shooting wide open at f/1.4 creates utterly gorgeous background blur that really accentuates subjects and sets them apart from their surroundings. Beautiful circular bokeh is rendered, however using the lens wide open at f/1.4 did produce what’s known as the cat eye bokeh effect, whereby specular highlights are rendered more of an oval shape towards the edge. I discovered that by stopping the lens down to f/2, it created circular bokeh of distant specular highlights right into the corners of the frame.
An inspection of our Applied Imaging tests confirmed exactly what I found from studying my sample images at close magnification in Lightroom. A high level of sharpness is resolved in the centre when it’s used at f/1.4, with the sweet spot between centre and edge sharpness being found at f/5.6. Sharpness figures do start to tail off beyond f/11 though as the introduction of diffraction starts to soften fine detail.
The way vignetting is controlled is a real strength of this lens. Shoot with the lens set to its maximum aperture of the f/1.4 and you’ll be hard pushed to notice that the edges are any darker than the centre in real-world images. Our corner shading tests reveal the corners are approximately 0.3EV darker than the centre at f/1.4, which reduces to less than 0.2EV by f/2.8.
As to be expected of a mid telephoto prime costing in excess of four figures, the optical performance isn’t compromised by distortion. I noticed a hint of green and purple fringing in real-world images along high contrast edges in images taken at f/1.4, but this is only really noticeable under very close inspection at high magnification and was easily dealt with using the defringe sliders in Lightroom.
All things considered, the lens does a very commendable job of controlling chromatic aberrations at wide apertures.