Sigma 70mm f/2.8 DG
Sharp shots and fine detail as standard
Get sharp close-ups with ultra-fine detail www. sigma- imaging- uk. com
This new full-frame 70mm Art lens is the first of Sigma’s ‘Global Vision’ line-up to deliver full 1.0x macro magnification. Build quality and finish is top-class: premium materials include Sigma’s TSC (Thermally Stable Composite) plastic and a brass mounting plate that features a weather-seal ring. Apart from the Sony-fit version, the lens is compatible with Sigma’s optional USB Dock for applying fine-tuning and firmware updates, and the Canon-fit edition is also compatible with in-camera corrections.
Autofocus is driven by a coreless DC autofocus motor. It’s not overly quick but is whisper-quiet and incredibly precise. Full-time manual override is available and, often more importantly for macro shooting, the electronically coupled fly-by-wire focus ring enables extremely fine adjustments. The optical design incorporates two top-grade FLD (‘Fluorite’ Low Dispersion) elements and two SLD (Special Low Dispersion) elements, along with one high refractive index element. Two aspherical elements are also incorporated.
The new 70mm lacks internal focusing. As such, the inner barrel extends dramatically at shorter focus distances. Sigma claims that this is to enable the best possible performance at every shooting distance. However, the working distance from the front of the lens during full 1.0x macro shooting can feel uncomfortably tight, at just 6cm compared with the 105mm lens’s 14cm.
Performance
Contrast and centre-sharpness are phenomenal between f/2.8 and f/11, and there’s impressively little drop-off towards the edges of the frame. Due to diffraction, there’s a fall-off in sharpness at very narrow apertures, but no worse than that of rival lenses. The lack of optical stabilisation might be frustrating for general shooting but would be of limited value for extreme close-ups.