Sigma 50mm f/1.4 EX DG HSM: Quality Wide Open


The Sigma 50mm f/1.4 EX DG HSM is a high quality, standard focal length lens which gives you an alternative to your own brand 50mm primes, with some added new features. These added features include an aspheric element for correcting chromatic aberrations, a rounded diaphragm for more pleasing bokeh, a large lens barrel to cut down on vignetting and special super multi-layer coatings on the lens to reduce flares. Along with fast autofocusing, it can definitely be an alternative to your own brand 50mm prime.

The problem is, with good quality optics comes a high price tag. Can the superior image quality be justified against the price compared to own brand 50mm lens?


The basic design of the lens is nothing out of the ordinary, being part of Sigma’s premium ‘EX’ line. On a crop sensor of 1.5x, you get the equivalent of a 75mm focal length and 80mm on a 1.6x camera. The aperture range goes from f/1/4 to f/16, with the glass consisting of 8 elements in 6 groups and one aspherical element. There are nine rounded diaphragm blades to get some pleasing bokeh and a minimum focusing distance of 0.45m (1.5 ft). The AF motor is Sigma’s Ring-type ultrasonic system that can also be switched into fully manual mode.

The filter thread is quite large at 77mm making for a chunky lens, which doesn’t rotate when focusing, all wrapped up in a package weighing a hefty 505g (17.8 oz). Quite substantial for a 50mm lens. The lens mount is made of metal with high-quality plastics for the barrel construction with a nice textured feel which you find on all EX lens. The whole optical assembly moves when focusing, but it is entirely enclosed within the lens barrel and recessed from the front of the lens stopping any stray light if you don’t have a lens hood attached. The hood, if used is a deep petal-type lens hood, further stopping any stray light.

Autofocusing is done via the (HSM) ‘HyperSonic Motor’ which is very smooth and accurate and links up well with Nikon, Canon, Sony, and Pentax systems. Older Pentax DSLRs may not be able to use the lens with AF, so will have to cope in full manual mode. The Canon mount locks in and works great with the lens’s AF, only seemingly struggling in extremely low light conditions. This was expected as it would be no matter the lens choice.

The 13mm focus ring doesn’t rotate when auto focusing and is very smooth in operation. It only needs to be turned 90° clockwise to go from infinity to 0.45m. On the side of the lens is a switch for changing between autofocus and manual mode. Even in AF mode, you can still use manual focus when needed. There is also a distance scale and depth of field scale on the front of the lens, although they have been set up to be used on full frame sensor bodies, so not much use if you have a crop sensor camera.


Image Quality

Firstly, using the lens on an APS-C sensor body gives impressive results with low distortion levels and when wide open it’s equally sharp as Canon’s own EF 50mm f/1.4 USM or Nikon’s 50mm f/1.4 D, but the own brand lens being better at smaller apertures. The lens is just as quick to focus and comparable with what Canon and Nikon have to offer. On a crop sensor, there is slight softness when the lens is wide open. Dropping to f/5.6 definitely sharpens things up.

On a full frame body, sharpness definitely improves when fully wide open. There is a little softness in the corners, but just like on a crop sensor stopping down vastly improves things and getting impressively sharp at f/8. There is some chromatic aberration, a small amount of vignetting is present but at lower levels than on a Canon or Nikon equivalent. The differences in sharpness for lenses used on a crop sensor or full frame body no matter which camera bodies used with a bit of stopping down, you still get extremely sharp results. The corners can become soft when the lens is wide open, but stopping down to around f/4 definitely cures things.

When it comes to lens flare, the recessed optics and lens hood do a great job of keeping stray light in check, especially with a 77mm front-end. Bokeh is very desirable at this focal length and this one doesn’t disappoint with nicely blurred backgrounds, giving a nice creamy look and great highlights in low light.

Sigma 50mm f/1.4 EX DG HSMCanon EF 50mm F1.4 USM
Diaphragm blades98
Filter thread77mm58mm


Although the lens is soft at the corners on a full frame, high-resolution body, this lens is definitely equal or better than brand equivalents. Sharpness is definitely better at large apertures with a little vignetting, but less than the rest. Chromatic aberration and distortion have also been reduced, making the lens a nice accompaniment to a standard zoom. Central sharpness has been a priority and this comes across at all focal ranges with both sensor types.

So although there is edge softness, it definitely copes well over other 50mm f/1.4 lenses and at f/1.4 where there is such a shallow depth of field, the softness would be hard to tell. The lens is clearly a chunky design not one of your lightweight, portable 50mm lens, but all that glass produces better optics and the extra weight is worth it.

The price of this lens may be the deciding factor as it is more expensive than brand equivalents. Thus, it’s really down to the decision of if the extra bit of image quality wide-open is worth the extra cost.

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