Launched last year, the optically stabilised Sigma 105mm f/2.8 EX DG OS HSM Macro is a wishlist come true for macro photographers. It has fully internal focusing, so there's no extension of the lens barrel at short focus distances.
The HSM (Hyper-Sonic Motor) autofocus is practically silent, very fast and extremely accurate. Manual focusing is wonderfully smooth and precise too, which is something that can't always be said for ring-type ultrasonic focus systems.
The focus rings in the Nikon 40mm, 60mm and (to a lesser extent) 85mm lenses are all a bit stiff and jerky. This makes very fine focus adjustments much easier to make on the Sigma. However, the Nikon 105mm f/2.8G AF-S IF-ED VR Micro has a smoother focus ring.
The Sigma 105mm's handling is supremely good, and its optical stabiliser works well in general shooting.
However, image quality is what matters most. There's not much to distinguish the Sigma and Nikon 105mm lenses, but the Sigma wins with class-leading sharpness at small apertures, ideal for macro shooting. It also has less colour fringing and distortion.
The only disappointment with the Sigma 105mm is that it's so expensive. It really does justify its price tag, but there are bargains to be had at the low end of the price range.
The Tamron 90mm f/2.8 SP AF Di Macro has earned a great reputation as a macro lens and, with superb image quality and refined manual focusing for close-up shooting, it's unbeatable value at the price.
However, while the Sigma 105mm and Tamron 90mm lenses are two of the best in the group, the Sigma 70mm f/2.8 EX DG Macro and Tamron 60mm f/2 SP AF Di II Macro are the least impressive.
If you're serious about your macro photography, the Sigma 105mm f/2.8 EX DG OS HSM Macro is the ultimate lens for the job.