The Sigma 50mm f/1.4 DG HSM A is definitely one of the very sharpest 50mm lenses we ever tested, with a totally outstanding performance at full aperture (see the “Optical performance” section further down). This makes it very useful for portrait photography or documentary images in low light. But it’s remarkable not only in terms of sharpness – the color correction is good and Sigma has managed to keep both distortion and vignetting at a minimum.
The lens is also very well built and has an elegant design with a body partly made of metal. The “A” in the model name stands for “Art”, which is Sigma’s name of their luxury series of lenses. The only real drawbacks of the Sigma 50mm f/1.4 DG HSM A is the abscense of weather seals. And the size and weight.
With a length of 10 cm and weighing 815 grams, this is indeed an unusally large and heavy nomal lens. But looking at the complex optical construction, it’s easy to see why. Sigma has put together 13 lens-elements in 8 groups, a lot more than the 7 elements used in the typical Planar construction found in most normal lenses.
The autofocus is powered by an ultrasonic motor which is rather silent. It focused perfectly with the camera used for this review (a Canon EOS 6D). But buyers who may experience focus errors can purchase Sigma’s USB Dock. A small gadget that fits on the lens and connects to a computer with a USB cable, making it possible to upgrade the lens firmware and calibrate the autofocus.
Sigma has not only built one of the world’s best normal lenses, with a retail price of around 950 USD it’s also surpricingly cheap. The Zeiss Otus Distagon 55mm f/1.4 APO and the Leica Summilux-M 50mm f/1.4 ASPH, which we also consider to be in the same league, cost about four times as much. Nice work Sigma!
**Reference Class**
Specifications
Sigma 50mm f/1.4 DG HSM A
Image circle: 24 x 36 mm (full frame)
Angle of view, horisontal: 40° (full frame)/27° (APS-C)
Filter thread: 77 mm
Minimum focus: 40 cm
Minimum aperture: 16
Dimensions: Length 10 cm, diameter 8,5 cm
Weight: 815 g
Other features: Ultrasonic motor (HSM). Aperture with nine blades. Lens hood and padded lens bag included. Compatible with the Sigma USB Dock. Available for Canon, Nikon, Sony and Sigma.
Visit Sigma’s product page for the Sigma 50mm f/1.4 DG HSM A. Click here.
Optical performance
Sigma 50mm f/1.4 DG HSM A
Measured focal length:
49 mm
Sharpness
For easier comparison with other tested lenses, we first present an MTF chart showing the result at both full aperture and at f/8. The chart below it show MTF at f/2.8.
With full frame:
Very good sharpness across most part of the image already at full aperture. The contrast decreases slightly towards the edges but it’s still an impressive result. Reducing the aperture a couple of stops to f/2.8 gives a quiete clear imrovement of the result. The contrast increases in the image edges and really small and fine details are reproduced more distinctly. This is particularly noticable with image sensors with very high resolution and no low pass filter. Stopping down further gradually increases the impression of sharpness and brilliance until you reach f/8. Here the lens is phenomenally sharp!
With APS-C:
Very good sharpness from center to corner already at full aperture but it still increases notably when the lens is stopped down to f/2.8. At f/5.6 and f/8 Sigma’s 50mm Art lens performs incredibly well, with very high contrast and detail (resolution) all the way to the corners.
Vignetting
With full frame:
Clearly noticable vignetting at f/1.4, low at f/2.0 and prctically gone at f/2.8.
With APS-C:
The vignetting is only barely visible at full aperture. After stopping down to f/2.0 it completely disappears.
Distortion
With full frame:
Not visible
With APS-C:
Not visible
