Tamron 28 200mm f/2.85.6 Di III RXD lens review
Andy Westlake evaluates Tamron’s new large-aperture superzoom for full-frame mirrorless cameras
If there’s a sure-fire way of telling which direction the camera market is taking, it’s by examining the new lenses being released by thirdparty makers. Like its main rivals, Tamron has now refocused its attention almost entirely in the direction of full-frame mirrorless, with five of its seven new lenses in 2019 being for Sony’s E-mount cameras. Now it’s added another, in the form of a broad-range superzoom – an area in which the firm has considerable expertise. But even a quick parse of the lens’s name reveals that the 28-200mm F/2.8-5.6 Di III RXD is above the norm, being the first of its type to boast such a large maximum aperture, rather than the more usual f/3.5 or f/4. It also offers impressively close focusing, ranging from 19cm at wideangle to 80cm at telephoto.
You might expect that the large aperture would command a significant price premium, but in fact the lens is set to go on sale for £799.99. This is very competitive compared to similar optics, with its most obvious rival, the five-yearold Sony FE 24-240mm F3.5- 6.3 OSS having a street price around £750. So with its unique combination of zoom range and maximum aperture, could this be an ideal all-in- one travel lens for Sony users?
Features
In terms of design philosophy, this new optic closely matches the rest of Tamron’s E-mount range. Despite its large aperture, it’s relatively small and lightweight, at 117mm long and 575g, which can be attributed to two design decisions. Tamron has adopted a modest 28mm view at wideangle, and omitted optical stabilisation, relying on the camera’s in-body image stabilisation (IBIS) instead. This also allows use of the same 67mm filter thread as its E-mount stablemates. But it means the lens is a poor match to
first- generation Alpha 7 series bodies that lack IBIS, while APS- C users will be better served by the optically stabilised 18-200mm F/3.5- 6.3 VC Di III.
Tamron says that the lens has been designed to deliver high resolution into the image corners. To this end, it has incorporated plenty of exotic optics in the 18- element, 14- group design, including two hybrid aspherical elements and two glass-moulded aspherical elements. These are joined by an extra-low dispersion (XLD) glass element and two low dispersion (LD) glass elements to minimise chromatic aberration. The lens is also designed to make full use of in- camera software corrections, to give the cleanest possible images.
That f/2.8 aperture may be the most eye- catching specification, but the good news is that it reduces only gradually on zooming in, dropping to f/3.2 at 32mm, f/3.5 at 44mm, f/4 at 54mm, f/4.5 at 80mm, f/5 at 115mm, and f/5.6 at 150mm. This counts as a two-thirds stop advantage across its range compared to the Sony 24-240mm f/3.5- 6.3.
The barrel boasts weatherproof construction, with seals around the zoom and focus rings, as well as the mount. A fluorine coating promises durable oil and water resistance for the front element, and a bayonet-mount petal-type hood comes in the box. The lens is fully compatible with Sony’s latest technologies such as Eye-AF and Fast Hybrid AF, and its firmware can be updated via the camera body if required, negating the need to buy an additional dock.
Build and handling
As previously mentioned, the 28-200mm f/2.8-5.6 is surprisingly compact given its specifications. In fact, it’s similar in size and weight to the firm’s 28-75mm f/2.8 Di III RXD, and 200g lighter and 6mm shorter than Sony’s 24-240mm f/4- 6.3.
Tamron has achieved this feat by using high quality plastics for the barrel construction. As a result, the lens handles very well, with the broad zoom ring falling readily to hand, and requiring a turn of approximately 90 degrees to traverse its full range. I had no problem with zoom creep, instead finding that the lens held its position when pointed vertically up or down, but a small switch allows it to be locked at the 28mm mark just in case. The manual focus ring operates smoothly, allowing precise adjustments on the rare occasions that it’s needed.
Autofocus
For focusing, Tamron has employed the same Rapid eXtra-silent stepping Drive (RXD) motor as in its recent 17-28mm f/2.8 and 28-75mm f/2.8 E-mount optics. This moves the focus group directly without any intermediate gearing, giving fast, silent autofocus for both stills and video use. Like most AF lenses for mirrorless cameras, manual focus exploits the same mechanism.
In practical use the autofocus works very well, and is generally limited more by the camera body than the lens itself. On the Alpha 7 III it’s excellent, giving rapid, decisive response with both static and moving subjects. Not surprisingly, the older Alpha 7 II
struggles a bit more, especially at the telephoto end in low light, taking noticeably longer to acquire focus. But as usual with on-sensor AF systems, there’s little to complain about with regard to accuracy.
Image quality
One big advantage of mirrorless systems over DSLRs is the additional flexibility they bring to optical design, by enabling lens elements to be positioned much closer to the image sensor. Tamron appears to have exploited this to produce a lens that delivers much better pictures than you might expect, given its large aperture and broad range.
Evaluated on the 24MP Alpha 7 III, the lens resolves impressive levels of detail in the centre of the frame, even at maximum aperture. Not surprisingly, it can’t maintain this level of performance across the entire image area, with sharpness gradually deteriorating towards the periphery. But even at f/2.8, the corner blurring isn’t excessive, and in real-world use you’ll probably lose more sharpness due to limited depth of field. Stopped down to its sweet spot around f/8-f/11, the lens gives pretty good results from corner to corner; it won’t match a prime or premium zoom, especially on high- resolution sensors, but for many purposes it’ll be plenty good enough.
As usual with this kind of lens, the degree of corner blurring also diminishes as you zoom in, with visibly better results at 50mm compared to 28mm. By the time you hit the 100mm mark, images are sharp across essentially the entire frame, even when shooting wide open. Zoom all the way to 200mm, and a degree of corner blurring returns, however it can be fixed by stopping down to f/11. But again, depth of field is likely to be a far bigger concern. Unlike older superzooms, the lens also maintains its sharpness really well for close- up shooting.
Typically superzooms suffer from curvilinear distortion, and the 28-200mm is no exception. However, its barrel distortion at 28mm is much less severe than usual for this kind of lens – perhaps a happy consequence of that relatively unambitious wideangle setting. But across most of the zoom range, it shows considerable pincushion distortion, so I’d recommend keeping compensation enabled in the camera’s menu. Likewise, it’ll make sense to apply corrections in raw processing for many subjects. No Adobe profile was available at the time of writing, but as a guide, I found applying values of +4 at 28mm, -10 at 50mm, -9 at 100mm, and -6 at 200mm to the distortioncorrection slider in Camera Raw gave good results.
Another characteristic flaw of superzoom lenses is colour fringing due to lateral chromatic aberration (CA), which is most visible towards the extremes of the zoom range. The 28-200mm is no exception, showing green and magenta fringing towards the corners of the frame, so again it’s essential to ensure in- camera corrections are enabled. Users of Adobe software will be pleased to find that it automatically compensates for this CA in raw processing using information embedded in the file metadata. Vignetting is also very apparent at large apertures, but it disappears on closing down a couple of stops.
One area where the lens really excels is with regards to bokeh, delivering beautifully defocused backgrounds when shooting at close range and large apertures. Credit to Tamron here, as this isn’t often a strength of superzoom optics. It’s also reasonably well-behaved when shooting into the light, showing relatively little image degradation due to flare and ghosting.
‘ The lens resolves impressive levels of detail in the centre of the frame’