Sigma 105mm f/1.4 DG HSM | Art lens
Although the Sigma 105mm f/1.4 DG HSM Art lens is highly specialised, it does a brilliant job for the purposes for which it has been designed. Portrait and wedding photographers should find it meets a lot of their requirements.
It could be a perfect fit for the studio photographer and a real boon for astrophotographers.
Announced in February 2018, the Sigma 105mm f/1.4 DG HSM | Art lens is distinguished by its super-fast f/1.4 maximum aperture, which can produce a paper-thin depth of focus for isolating subjects from potential background distractions. This is a highly specialised and eye-catching lens with a huge front element, removable tripod collar and foot and a large cylindrical lens hood that is made from carbon fibre-reinforced plastic. Big and bulky for a 105mm lens, it is 131.5 mm with a diameter of almost 116 mm and an overall weight of just under 1.65 kilograms.
Side view of the Sigma 105mm f/1.4 DG HSM Art lens without the supplied lens hood but with the tripod collar attached. (Source: Sigma Photo)
This lens has been called the ‘bokeh master’ by many, and with justification. Its optical design consists of 17 optical elements in 12 groups, an unusually large number of elements for a prime lens.
The optical design of the Sigma 105mm f/1.4 DG HSM Art lens showing the positions of the exotic glass elements. (Source: Sigma Photo)
Three FLD glass elements sit well forward in the optical design (shown above) with two SLD glass elements a short distance behind them. A single aspherical lens element is located at the back of the lens close to the lens mount to control distortion and spherical aberrations and improve overall sharpness. The objective of the design is to minimise axial chromatic aberration while admitting plenty of peripheral light and at the same time reducing sagittal coma flare.
A Super Multi-Layer Coating has been applied to suppress flare and ghosting and provide optimal contrast and colour fidelity in contrasty lighting conditions. In addition, the rounded nine-blade diaphragm contributes to a pleasing bokeh quality.
Autofocusing is driven by an integrated HSM (Hyper Sonic Motor) that operates quickly and almost silently and uses an updated algorithm to produce smoother focusing performance. The HSM also permits full-time manual focus control simply by rotating the focus ring at any time.
The lens is supplied with a removable tripod collar (TS-111), front and end caps plus the LH1113-01 cylindrical lens hood, the PT-21 protective cover and a semi-rigid nylon carry case. A printed multi-lingual ‘Owner’s manual’ is supplied on a large double-sided sheet of paper, which is folded to fit into the box.
Who’s it For?
As noted, this is a highly specialised lens which won’t have general appeal because of its size, weight, single focal length and high price tag. Its size and bulk will mean it’s not easy to fit into the average camera bag – especially when it’s in its large, box-like padded case. But these are likely to be minor issues for its target market – primarily portrait and event (wedding) photographers.
The 105mm focal length hits a ‘sweet spot’ between traditional 85mm and longer 135mm portrait lenses. The 105mm focal length will suit both studio and environmental portraitists, especially the latter as it can be used with available lighting under a wide range of conditions.
A stand-out feature of the lens speed is the greater control it provides over depth of field for isolating subjects, making it easier to work creatively with selective focus than slower lenses. The f/1.4 aperture can soften almost any busy background.
This lens is also unrivalled for low-light shooting. While its size makes it a bit conspicuous for street shooting in daylight, at night it’s less noticeable, allowing photographers to use low ISO settings for minimal noise and take advantage of the IBIS in Sony’s mirrorless cameras. For astrophotography, the optical system is designed to minimise sagittal coma flare, making this lens ideal for shooting the night sky.
When shooting with wide apertures in daylight hours, such a fast lens makes it likely users will run out of shutter speed adjustments, so it’s worth noting the size of the filters this lens accepts. Neutral density filters may be required and they’re neither widely available or cheap (AU$350+).
In addition, it would be challenging to try fitting a gelatine filter holder to this lens when the lens hood is in place. Either way, the sheer size of both glass and gelatine filter kits adds to the difficulty of packing this lens into a camera bag.
Removing the tripod collar makes the lens take up less space and it can become easier to use for handheld shooting and video recording in challenging environments like live performances, where the 105mm focal length can prove useful. Unfortunately, this lens isn’t compatible with existing teleconverters.
Build and Ergonomics
In line with expectations for Sigma’s Art series lenses the 105mm f/1.4 DG HSM lens is very solidly built. Sigma has made use of Thermally Stable Composite plastic for much of the lens barrel, with a brass bayonet mount to provide rigidity and mounting precision.
Angled view of the 105mm f/1.4 DG HSM Art lens showing the large front element. The focus slider switch is also indicated in this picture. (Source: Sigma Photo.)
The front element (shown in the illustration above) has a diameter in excess of 80 mm and it set back roughly 5 mm from the tip of the lens barrel. The inner side of this 5 mm wide band is threaded to accept 105 mm filters while its outside has a 20 mm wide contoured band where the supplied lens hood is attached.
As mentioned, the hood is made from matte black carbon fibre reinforced plastic and has a ribbed inner surface to suppress reflections. It attaches via a screw-down clamp and can be reversed over the lens barrel for transport and storage.
The lens barrel slopes inwards from the hood for about 23 mm to meet the focusing ring, which is 33 mm wide and almost entirely clad in ridged rubber but ends in a sloping, 5 mm wide unridged band. It’s easy to use this ring because the grip is secure and it is nicely damped and turns easily.
Behind this band the lens barrel remains almost cylindrical for approximately 28 mm to provide space for a distance scale and AF/MF slider switch before stepping inwards to provide an attachment area for the supplied tripod collar, which is 17 mm wide. The tripod collar can be rotated by loosening its locking knob and index marks are stamped on the lens barrel to show the positions for vertical and horizontal alignment of the camera. An Arca-type compatible foot allows trouble-free attachment to most tripods and monopods. When the collar is removed, the supplied PT-21 Protective Cover should replace it to ensure more comfortable handheld use.
The lens barrel curves inwards and then flattens out for the 40 mm long section of the barrel that ends in the lens mount, which is made from brass to provide high durability plus accurate fitting. A thin rubber gasket encircles the mount to keep it dust- and splash-resistant.
Even at relatively wide aperture settings, even with in-camera lens corrections disabled, the review lens turned in a superb performance in our Imatest tests. Measurements from the centre of the frame between f/1.6 and f/8 comfortably exceeded expectations for the camera’s 24-megapixel sensor, as did those taken roughly half way out from the centre between f/2 and f/5.6.
Resolution fell just short of expectations with measurements close to the periphery of the frame up to f/2.2 but rose above the expected value at f/2.5 and remained there until between f/5.6 and f/8. The graph below shows the results of our tests.
Measurements made on ARW.RAW files recorded simultaneously with the JPEGs delivered even higher resolutions. Samples are shown in the TESTS section of this review.
With no in-camera corrections applied, we were able to use the JPEG files to evaluate lateral chromatic aberration. While chromatic aberration ventured into the ‘low’ category at the widest aperture settings, it remained within the ‘negligible’ range once the lens was stopped down beyond f/2, as shown in the graph of our test results below. (The red line marks the boundary between negligible and low CA.)
Switching off the in-camera corrections also allowed us to assess the effects of vignetting and rectilinear distortion on JPEG files from the camera, although we checked a few of the raw files recorded simultaneously, which were converted into TIFF format with all optical adjustments disabled. Slight vignetting was evident at f/1.4, which is to be expected. Fortunately most of it was gone by f/2.
Rectilinear distortion is seldom encountered in telephoto lenses and we didn’t find any in the test shots we took. Autofocusing was also very good; on the Sony α7 II the lens was quick to lock onto subjects within its focusing range as long as it could find an edge. Hunting only occurred with very dimly-lit, low contrast subjects.
The lens hood made it easy to avoid the effects of flare and ghosting, although it was possible to create some veiling flare when the lens was pointed at a bright light source. Stopping down to f/16 produced some nice sunstars, although most users would avoid shooting directly into the sun with a lens like this.
Bokeh at wide apertures was very smooth and the wider apertures provided plenty of scope for differential focusing to produce sharp subjects against attractively-blurred backgrounds. It doesn’t get much better than this lens.
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Picture angle: 23.3 degrees
Minimum aperture: f/16
Lens construction: 17 elements in 12 groups (including elements)
Lens mount: Sony E
Diaphragm Blades: 9 (circular aperture)
Weather resistance: Yes
Focus drive: Ring-type Hyper Sonic Motor
Stabilisation: No, relies on SteadyShot inside IBIS in Sony cameras
Minimum focus: 100 cm
Maximum magnification: 0.12x
Filter size: 105 mm
Dimensions (Diameter x L): 115.9 x 131.5 mm
Weight: 1645 grams
Standard Accessories: Front and rear caps, LH1113-01 Lens Hood, TS-111 Tripod Collar, PT-21 Protective Cover, semi-rigid case
Distributor: C.R. Kennedy & Company, (03) 9823 1555
Based on JPEG files captured with the Sony α7 II camera.
Based on ARW.RAW files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.
Vignetting at f/1.4.
Portrait shot; ISO 100, 1/800 second at f/1.4.
Portrait shot; ISO 100, 1/2500 second at f/2.2.
Close-up; ISO 100, 1/800 second at f/1.4.
Close-up; ISO 100, 1/200 second at f/1.4.
Close-up; ISO 100, 1/800 second at f/1.4.
Close-up; ISO 100, 1/1000 second at f/1.4.
Close-up; ISO 100, 1/1000 second at f/2.8.
Close-up; ISO 100, 1/1000 second at f/1.4.
Selective focusing; ISO 100, 1/6400 second at f/1.4.
Sunstars plus slight veiling flare at f/16; ISO 100, 1/640 second.
ISO 100, 1/200 second at f/10.
ISO 100, 1/800 second at f/6.3.
ow-light shot; ISO 100, 1/125 second at f/13.
Night scene; ISO 800, 1/8 second at f/5.6.
Night scene; ISO 800, 1/20 second at f/5.6.
Night scene; ISO 1600, 1/4 second at f/4.
Night scene; ISO 1600, 1/6 second at f/4.
RRP: AU$2699; US$1599
- Build: 9.2
- Handling: 8.9
- Image quality: 9.0
- Autofocusing: 9.0
- Versatility: 8.6