Sigma 40mm F1.4 DG HSM Review
The Sigma 40mm F1.4 DG HSM is a wide normal-length prime lens for full-frame and APS-C DSLR cameras. It offers the equivalent angle of view as a 60mm lens on an APS-C system (depending on the exact crop factor).
The Sigma 40mm F1.4 DG HSM features a rounded 9 blade diaphragm which creates an attractive blur to the out of focus areas of the image and an optical design comprised of 16 elements in 12 groups, including three F Low Dispersion (FLD) and three Special Low Dispersion (SLD) elements.
It has a minimum focusing distance of 40cm /15.7in and a maximum reproduction ratio of 1:5.3, and an aperture range of f/1.4-f/16. The lens has a dust- and splash-proof structure and there is a special water- and oil-repellent coating on the front lens element.
The Sigma 40mm F1.4 DG HSM lens retails for £1199.99 / $1399.99 in the UK and the US, respectively.
Ease of Use
Weighing in at 1.2kg and measuring 13.1cm in length, the Sigma 40mm F1.4 DG HSM is a massive lens given its focal length, signficantly larger and twice the weight of the very similar Sigma 35mm F1.4 DG HSM.
As seen in the photos below, it's a good match for a full-frame DSLR camera like the Canon EOS 5DS R that we tested it with, but it looks and feels out of place on a smaller APS-C camera like the Canon EOS 80D.
As with all recent Sigma lenses that we've tested, the build quality is once again excellent. The lens has a plastic shell with a mixture of metallic parts and a new compound material, TSC (Thermally Stable Composite) used inside. It incorporates a brass bayonet mount that's supposed to be more durable, according to Sigma.
In terms of features, the Sigma 40mm F1.4 DG HSM offers all the basics that you need from a prime lens. The main exception is the lack of built-in Vibration Reduction, although the very fast maximum aperture of f/1.4 mostly makes up for this.
Focusing is usefully internal and manual focusing is possible when set via the Focus switch on the lens barrel. Full-time manual focus override is also available at any time simply by rotating the focus ring.
A clear distance scale in both feet and meters runs from the closest focusing distance of 40cm / 15.7in. to infinity.
The focus ring is pleasingly wide and ridged for easier grip. There are no hard stops at both ends of the range, making it a little more difficult to set focus at infinity. Polariser users should be pleased that the 82mm filter thread doesn't rotate on focus.
When it comes to auto-focusing, the Sigma 40mm F1.4 DG HSM zoom is a quick performer, taking about 0.15 seconds to lock onto the subject when mounted on the Canon EOS 5DS R that we tested it with.
We didn't experience very much "hunting" at all, either in good or bad light, with the lens accurately focusing almost all of the time. It's also a very quiet performer, thanks to the built-in HSM (Hyper Sonic Motor), which makes this lens well-suited to video recording.
The Sigma 40mm F1.4 DG HSM ships with a good quality padded case and also a good quality plastic petal-shaped lens hood with a locking mechanism. It accepts 82mm filters.
At the 40mm focal length the angle of view is 56.8 degrees.
Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, can be detected in some shots but they are not very prominent at all.
With the lens set to its maximum aperture of f/1.4, there is significant light fall-off in the corners. Stopping-down to f/4 virtually eliminates this.
The Sigma 40mm F1.4 DG HSM produces quite nice sunstars when stopped-down to f/16 or f/22.
The Sigma 40mm F1.4 DG HSM isn't claimed to be a macro lens, but it delivers quite good performance nonetheless. It has a minimum focusing distance of 40cm/15.7in and a maximum magnification ratio of 1:5.3. The following example demonstrates how close you can get to your subject, in this case a Compact Flash memory card.
Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc. In the Sigma 40mm F1.4 DG HSM lens, Sigma have employed an iris diaphragm with nine rounded blades, which has resulted in very nice bokeh in our view. We do realise, however, that bokeh evaluation is subjective, so we've included several examples below.
In order to show you how sharp this lens is, we are providing 100% crops on the following page.