Lens Reviews / Sigma Lenses i Lab tested

105mm	$636 average price

SLRgear Review
April 13, 2012
by Andrew Alexander

The Sigma 105mm EX DG OS HSM is an update of a venerable macro lens produced by Sigma for several years. The new lens is a complete overhaul of the design: a new layout of elements, optical stabilization and HSM focusing technology make up the large list of changes.

The Sigma 105mm EX DG OS HSM was designed as a full-frame lens, and on ''sub-frame'' APS-C sensor-based camera bodies the lens provides an equivalent field of view of either 168mm (Canon) or 158mm (Nikon and others). The lens is available in Canon, Nikon, Pentax, Sigma and Sony mounts.

The lens takes 62mm filters, ships with a round lens hood, and is available now for around $950.

Sharpness
The Sigma 105mm ƒ/2.8 EX DG OS HSM provides a very sharp image even wide open at ƒ/2.8, but for maximum sharpness you need to stop down to ƒ/5.6. There are traces of corner softness at ƒ/2.8, which settle down nicely at ƒ/4, and all but disappear at ƒ/5.6. Performance at ƒ/8 is more or less the same as ƒ/5.6 (though according to the numbers, just very slightly less sharp). Diffraction limiting sets in by ƒ/11, though you don't notice any practical impact on sharpness until ƒ/16, and even then, it's still very good. At ƒ/22 we begin to see some light softness across the frame.

The previous version of the lens could stop down as far as ƒ/45, but we noted extreme softness at this or the ƒ/32 setting - probably better that Sigma just removed these settings, as they didn't provide very useful results.

Chromatic Aberration
Chromatic aberration is kept very much in check with this lens; there is some to speak of in the corners when the lens is used on a full frame body (in this case, the Canon 1Ds mk III), but it isn't by any means excessive. Peeping at 100% crops, you'll note very light magenta fringing in the corners on the full-frame sample images - but it's very light indeed.

Shading (''Vignetting'')
Mounted on the sub-frame Canon 7D, the Sigma 105mm ƒ/2.8 showed very little corner shading - just 1/3 EV darker in the corners, when set to ƒ/2.8. At any other settings, there is no light falloff.

Mounted on the full-frame Canon 1Ds mk III, there was a bit more falloff - more so when used wide open at ƒ/2.8. In this case the corners are over 3/4 darker than the center. At ƒ/4, the corners are just over 1/3 darker than the center. At smaller apertures, there is no problem with light falloff.

Distortion
The Sigma 105mm ƒ/2.8 EX DG OS HSM produces no meaningful distortion whatsoever, on either the sub-frame 7D or full-frame Canon 1Ds mkIII.

Autofocus Operation
The Sigma 105mm is a welcome advancement from the previous version, with its implementation of HSM focusing. Autofocus is moderately fast and near-silent, and results can be overridden by just turning the focusing ring. It took just over a second to go through the lens' focusing range - as a macro lens, there is a lot of focus travel. The front element does not turn during focusing, making life a little easier for polarizer users.

Macro
The Sigma 105mm provides excellent macro performance, offering full 1:1 (100%) macro reproduction, with a minimum close-focusing range of 31 cm (12 inches).

Build Quality and Handling
The Sigma 105mm ƒ/2.8 EX DG OS HSM is a fairly beefy optic, made lighter by its use of plastic components (725g, 26 oz). It's finished with Sigma's matte grey texture and offers a metal mount, and plastic 62mm filter threads. The lens is noted as having a splash-proof design.

The lens is a complete redesign of the previous version: it now features 11 lens groups, with 16 elements, of which one is a Special Low Dispersion (SLD) lens, another is a high refractive index SLD lens. There are now nine rounded diaphragm blades instead of eight straight ones, to improve bokeh performance. Focusing is by way of a floating focusing system that moves two different lens groups in the optical path. And to top it all off, Sigma has thrown in optical stabilization, very useful for when you don't want to bring a tripod into the field.

The lens offers a few control surfaces of note: in addition to the focusing ring, there is a small panel on the side of the lens which features a switch to enable or disable autofocus, and a switch to enable image stabilization in mode 1 or mode 2, or disable it completely. There is also a focus limiting switch, offering options of 30cm - 45cm, 45cm - infinity, and no limit (30cm - infinity).

The lens also provides excellent scales. There is a distance scale in feet and meters, as well as reproduction ratios as the lens is focused towards its close-focusing distance. However, there are no depth-of-field indicators, nor is there an infrared index marker.

The focusing ring for the lens is very nice - over an inch wide, composed of rubber with deep ribs. Manually focusing with the ring is stiffer than usual, but this is what you want for macro work so you don't disturb a carefully focused scene. There are no hard stops at the close or infinity ends - an increase in resistance lets you know there's no point to focusing further.

Sigma's OS (Optical Stabilization) technology features in this lens, which in our testing provides 2-2.5 stops of stabilization performance. It makes a slight whirring noise when it's activated. Our testing noted some poor performance in this system when used with a shutter speed of 1/60s; otherwise, it works as advertised.

The lens ships with a round lens hood, ribbed and painted a smooth black on the interior to reduce any flare. Sigma also includes the HA 680-01 subframe hood adapter, which is intended for use when the lens is used with (obviously) sub-frame cameras such as the 7D. Without the adapter, the hood adds 2 inches to the overall length of the lens - with the adapter, that goes up to around 4.

It's worth noting that there is no compatible tripod adapter for this lens. It is compatible with Sigma's 1.4x and 2x teleconverters.

Alternatives

Sigma 105mm ƒ/2.8 EX DG Macro ~$-
Now discontinued by Sigma, the original 105mm macro is a bit sharper than the new OS HSM version: results for CA and corner shading were also slightly better, too (though there was a slight trace of distortion).

Canon EF 100mm ƒ/2.8L Macro IS USM ~$1,000
Overall, the Sigma is a hair sharper than the Canon and produces less corner shading, but the Canon is more resistant to chromatic aberration. There isn't a significant price advantage for the Sigma in this case, and the offer more or less the same feature set.

Nikon 105mm ƒ/2.8G IF-ED AF-S VR Micro ~$1,000
The Nikon 105mm Micro was one of the first lenses we tested here at SLRgear - we don't even have a full-frame test for it. Based on the results from the DX sensor of the D200, it looks like the Sigma is slightly sharper, though the Nikon does show impressively low CA and almost no distortion.

Pentax 100mm ƒ/2.8 Macro SMC P-FA ~$-
Possibly the sharpest of the macro lenses in this category, it's long since been discontinued and replaced by the P-D FA model which we have not yet tested. Results for CA, light falloff and distortion were all excellent, and also had an excellent feature set for macro work.

Sony 100mm ƒ/2.8 Macro ~$800
One of the better values in this category, the Sony offered good results for sharpness, though the Sigma is sharper at wider apertures. Stopped down, it was excellent. CA performance is all-around excellent, and it distorts very little.

Conclusion
Sigma has produced an excellent macro lens in the 105mm ƒ/2.8 EX DG OS HSM - it does away with an antiquated and confusing focusing system by using the HSM system, and offers optical stabilization. You'll want to be careful to avoid the 1/60 shutter speed when the OS system is in use, as it tends to do more harm than good.

Product Photos

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.