Tamron 2875mm f/2.8 Di III RXD
How does the first third-party standard zoom for the Sony FE mount shape up? Michael Topham tries out one of the first working samples
Michael topham puts the first third-party zoom for sony Fe mount to the test
It was only a matter of time before the popularity of Sony’s Alpha 7 series started to influence third-party lens manufacturers. At the beginning of the year, Tamron released the 28-75mm f/2.8 Di III RXD – the first third-party standard zoom for Sony’s full-frame mirrorless range.
Until recently, users of the Sony Alpha 7 series have had the choice of four standard zoom lenses, excluding those that can be mounted via an adapter such as Sigma’s MC-11. There’s the basic Sony FE 28-70mm f/3.5-5.6 OSS (£395), the popular FE 24-70mm f/4 ZA OSS Vario-Tessar Carl Zeiss T* (£749) and the sensational Sony FE 24-105mm f/4 G OSS (£1,199), all of which benefit from optical steady shot (OSS). We must not forget the ludicrously impressive Sony FE 24-70mm f/2.8 G Master either (£1,849). Tamron’s offering isn’t as wide as three of these lenses, but it still has plenty going for it.
Features
A standard zoom falls into one of three categories – entry level, mid range or professional. In Sony FE terms, this Tamron zoom is squarely mid range. While its 2875mm coverage means it isn’t as wide as a 24-70mm lens, what you lose at the wide end you gain at the long end. Key benefits are its constant f/2.8 maximum aperture and lightweight construction. Compared to a pro-spec standard zoom such as Sony’s FE 24-70mm f/2.8 G Master, which weighs a hefty 886g, this lens is over 300g lighter. Tamron has made every effort to keep the lens as compact as possible, too. It measures 117.8mm long when fully retracted, features an internal-focusing (IF) system to ensure the front element doesn’t rotate, and a closefocusing distance is preserved across the entire focusing range. It has a minimum-focus distance of 19cm at the wideangle end, which extends to 39cm at full telephoto.
This zoom features an entirely new optical design. It’s made up of 15 glass
elements in 12 groups, and to control aberrations and produce stable resolution across the zoom range, Tamron has equipped the lens with Extra Low Dispersion (XLD) glass. The hydrophobic fluorine coating on the front element is said to be highly resistant to fingerprints and its nine aperture blades are designed to render attractive bokeh in out- of-focus areas at wide apertures.
The lens debuts Tamron’s new Rapid eXtra-silent stepping Drive (RXD) – a highspeed AF drive system that has been designed to operate very quietly, making it well suited for times when you want to work discreetly. Tamron has opted not to fit the lens with its Vibration Compensation (VC) system; Alpha 7-series users can instead take advantage of their camera’s in-body stabilisation. At the front, it accepts screw-in filters and adapters via a 67mm filter thread. It also has a bayonet mount to accept the petal-shape plastic lens hood that’s supplied with the lens.
Build and handling
Unlike Tamron’s ‘SP’ range of lenses, which are known for their metal build, this lens is mostly made of polycarbonate. The idea of using highgrade plastic as opposed to metal is to strip the lens of any unnecessary weight. It doesn’t have quite the same rock-solid feel as Tamron’s premium SP optics or Sony’s pro-spec standard zooms, but feels more than robust enough for everyday use and is a standard above most entry-level standard zooms. The mount, however, is a robust metal. The finish of the matte-black barrel with its white numbering and lettering is excellent. To provide extra reassurance in demanding environments, the lens has a weather-tight rubber seal that was highly effective at keeping sand and moisture at bay during testing at the coast.
In terms of its size, it’s a similar diameter to the Sony FE 24-70mm f/4 ZA OSS VarioTessar Carl Zeiss T* lens, but is around 20mm longer. With no focus switches or focus- distance window, it has a minimalistic look, and whereas the zoom ring is rubberised, the focus ring is ribbed plastic. Zoom operation is smooth and it requires less than a quarter turn of the ring to go from wide to telephoto and back. It has a good level of resistance to prevent creep and the super-smooth manual-focus ring makes fine focusing adjustments enjoyable.
Handling wise, this zoom feels neither too big nor too small and rests comfortably in the palm of your hand. Its build quality and finish can’t be faulted for the price. You don’t get premium features such as a focus-mode switch, focus-hold button or zoom-lock switch, but then again, these features are typically found on lenses with a much higher price tag.
Autofocus
Tamron has designed the lens to be compatible with all focus modes and focus area settings on Sony’s latest Alpha 7-series cameras. This includes the Direct Manual Focus (DMF) feature that enables Sony cameras to instantly switch between autofocus and manual focus by rotating the focus ring whilst the shutter button is half depressed. Side-by-side testing with the Sony FE 24-70mm f/4 ZA OSS Vario-Tessar
‘Its build quality and finish can’t be faulted for the price’
Carl Zeiss T* lens demonstrated it’s just as fast at acquiring autofocus on static subjects and is reasonably snappy at keeping apace with moving subjects in continuous AF mode, with only occasional minor hunting at longer focal lengths. The RXD stepping motor unit keeps AF operation very quiet indeed.
Image quality
To understand how the lens performs optically, it was tested with both Sony’s high-resolution A7R III as well as the more recent Sony A7 III. It delivered impressive results, even on Sony’s most demanding full-frame sensor. Its strength is centre sharpness. When shooting wide open at f/2.8, sharpest results were achieved around 50mm. Centre sharpness improves across the range by stopping down to f/4, and it’s marginally sharper in the centre towards the middle and far end of its zoom range than it is at wideangle. Corner sharpness, especially between f/2.8 and f/4, is this lens’s weakness. To achieve the best results from edge to edge, you’ll want to use the lens around f/8.
Uncorrected files show considerable distortion. This, typically of a standard zoom, is of the barrel type at wideangle, quickly changing to pincushion across most of the zoom range. The good news is that the lens is compatible with in- camera lens corrections, which users will want to ensure are activated before shooting. As for vignetting, this is very prominent in uncorrected files at f/2.8. It’s not quite as severe in the middle of the range as it is at either end of the zoom, and reduces considerably by stopping down to f/4 or f/5.6. A study of raw files revealed that the lens exhibits chromatic aberration through its zoom range. After identifying traces of green and purple fringing along some high- contrast edges, I compared raw files beside their respective JPEGs that were subject to in- camera corrections. This clearly showed that the fringes of colour were effectively removed in the latter.