Sigma 105mm F2.8 EX DG Macro OS PDF Print E-mail
Written by Richard Kilpatrick   
Monday, 01 October 2012 00:00

Sigma's revised family of Macro lenses now sports Optical Stabilisation and a maximum aperture of F2.8 on all models over 100mm. Of these, the lightweight, compact 105mm Macro is an attractive option, particularly for a new generation of photographers returning to full-frame with the consumer-focused Nikon D600 body and Canon's latest entry, the 6D. Fast, full-frame 105mm lenses are appealing for portraiture as well, so the 1:1 repro, weather resistance and general compact dimensions position this not only as the cheapest of a trio, but for many, the most desireable. Richard Kilpatrick puts the new lens through its paces in Nikon fit.

There's no doubt that for my own forays into Macro photography, I tend to prefer working with the Sigma SD1. There's a strong argument to be made for retaining as much detail as possible when your goal is to get in close and achieve that 1:1 reproduction that will let you either print a subject only 23mm long up to 30" wide, or crop tightly for magazine/online reproduction. However, working with the SD1 requires careful lighting, focus and a bit of time, as it's not going to jump in and do the work for you. With the new 105 and 180mm Macro lenses only available in full-frame Nikon fit, I had little choice but to put them on the class-leading D800E - with 36Mp and no anti-aliasing filter, it offers a very similar 'capture' resolution for 1:1 to the SD1, albeit with a Bayer CFA - and the newly launched D600.

Autofocus has been taken for granted now for almost 35 years - even those earliest AF interchangeable lens SLRs are pushing 30 - and yet many Macro enthusiasts insist on working with manual focus. It's just not necessary with technology's currect position - the lens can react quickly enough, stabilisation negating that essential tripod for many subjects, and AF sensors are sensitive enough to work in a full automated way. It may not be right for the purists, but if you're jumping into taking pictures on a DSLR and expecting the same simplicity and instant gratification - albeit at much higher quality - that your Macro button on a compact gives, it's entirely feasible.




Testing on the D600 is particularly revealing, as this relatively low-cost full-frame body is likely to be a popular enthusiast option. The 105mm Macro - with a low SRP and a street price in the UK around £550 from reputable, authorised dealers, is an affordable model that will provide not only true Macro with a working distance of 31cm (complex internal focusing chages the pure optical relationship between the lens/camera and subject) at F5.3, but also a rather classic portraiture lens. And of course, with full-frame coverage, it's suitable for all bodies with the appropriate mount; the tighter crop and higher spatial resolution of models like the Nikon D3200 and Sony Alpha A65 SLT could theoretically provide immense reproduction of tiny subjects.


Dronefly, captured with Nikon D800E


The D800E is an unforgiving body, and really reveals any flaws in optics and technique in equal measure. Any lens which shines on this body is going to impress.

A substantial upgrade from the previous 105mm Macro, the solid EX DG OS model weighs 725g and includes a focus limiter and dual-mode stabilisation, for action and panning shots as well as correcting shake. As with most Sigma lenses with full-frame coverage, an extension hood is provided for APS-C users though that, combined with the standard hood, can yield a combination approaching the working distance of 312mm. Typically for an EX DG lens, a soft, padded case is included and in the UK for UK-sourced lenses, a 3 year warranty applies.

Unlike its longer, heavier siblings, the 105mm does not have a tripod collar. It also features a useful, manageable 62mm filter size, sufficient for most dedicated Macro flash systems and even older ones when working with APS-C and stepping rings.

Sigma's specification is highly competitive against rival lenses - 9-blade rounded diaphragm, HSM AF, internal focusing (which, due to the complex formula, does result in 'focus breathing' when composing at 1:1) and solid construction. The results are what truly impresses, however. As you would expect, there is minimal distortion and excellent contrast, with little falloff even at F2.8 and distant subjects. As a portrait lens, it offers a natural rendering with delightful bokeh - I'd grab it in a second for environmental portraiture and be ready for interesting fauna and flora alike. Focus can hunt a little at the extremes - the out of focus image being so soft between 31cm and infinity that any camera will struggle to get a fix - but when working at close distances with mobile subjects, it responds quickly.




When working with the Nikon bodies - both the D600 and D800E sport advanced AF sensors with 3D tracking and very sensitive centre points, sufficient for the real F5.3 value reported at 1:1 repoduction (all Macro lenses, and bellows, reduce their effective aperture with extension - some camera bodies report the variation, some do not, but all should meter correctly) - the 105mm proves to be a responsive and accurate lens. Spotting a moment out of the corner of my eye, quickly grabbing the D600 with 105 still attached captured this dog begging for lunch.




And whilst we're on the subject of lunch...




These files can be cropped dramatically. The Drone Fly at the beginning of this article is already slightly croppped, but even then, when working with a 36Mp camera it's possible to reveal this detail in the insect's eyes. Slightly excessive sharpening has been applied to this Lightroom screenshot, to emphasise the compound eye; the Bayer CFA does begin to lose some detail and at F16, diffraction can begin to be an issue - though not for most output formats, and moving to F22 and above when working with appropriate lighting will give impressive results when reduced for output.




As a lens to add to a working set, the 105mm Macro is already a good choice. Sigma's latest interpretation of the design - with low cost, versatile stabilisation and quick AF - is excellent. Moving away from the Macro end, it shows potential as a great portrait and product photography lens as well. It's hard to think of any downsides to the 105 EX DG OS, bar finding yourself tempted to spend more time than you may otherwise be comfortable hanging around with characters like these...