Tamron 17-28mm F2.8 Di III RXD Review
The 17-28mm F2.8 Di III RXD is Tamron's second ever lens for Sony's now exxtensive range of Alpha E-Mount full-frame and APS-C mirrorless cameras.
This new wide-angle zoom lens features a constant aperture of F2.8 throughout the range, an impressive minimum focus distance of 0.19m, an all-new RXD (Rapid eXtra-silent stepping Drive) focus motor for quiet and fast AF operation, and a moisture-sealed construction.
The optical formula is comprised of 13 lenses in 11 groups, including three aspherical lens elements, two LD (Low Dispersion) lens elements and one XLD (eXtra Low Dispersion) lens element, and it has an iris diaphragm with nine rounded aperture blades for better bokeh effects.
The Tamron 17-28mm F2.8 Di III RXD lens is officially priced at £899 / $999 in the UK and USA respectively, and is available to buy now.
Ease of Use
Considering that it offers a fast and constant maximum aperture of F2.8, the Tamron 17-28mm F2.8 Di III RXD lens is surprisingly compact and lightweight, measuring 10cms in length and weighing in at only 420g.
In addition to using it on full-frame cameras like the Sony A7 III that we tested it with, you can also use this lens on a smaller APS-C body like the Sony A6000 series of cameras, where the equivalent focal length changes to a still useful range of 24.5-42mm.
As demonstrated by the product images above and below, the Tamron 17-28mm F2.8 proved to be a perfect match for a full-frame camera like the Sony A7 III.
Build quality is fine, but not quite as good as recent Tamron "SP" branded lenses that we've reviewed. The Tamron 17-28mm F2.8 Di III RXD feels solid enough in your hand, despite its mostly polycarbonate construction.
"Designed in Japan" is proudly emblazoned on the side of the lens, but it's actually made in Vietnam.
There are no other external features on the lens other than the zoom and focus rings. The zoom ring is generously wide and has a ridged, rubberised grip band. There is no focus lock switch as on many other Tamron zooms.
The lens does not extend when fully zoomed out to 28mm - if you look carefully, it's actually at its longest when set to 17mm, although it still doesn't extend past the end of the lens barrel.
The focusing ring is much narrower than the zoom ring, making it more difficult to locate in a rush, and there are not hard stops at either end of the range.
The Tamron 17-28mm F2.8 Di III RXD features an all new high-speed RXD (Rapid eXtra-silent stepping Drive) that allows virtually silent auto-focusing, making it well-suited to video use.
Importantly, the lens is also fully compatible with the "Direct Manual Focus (DMF)" system feature of Sony cameras that enables the user to instantly switch between autofocus and manual focus.
In use, we found the new focusing system to be very quiet and satisfyingly fast with the lens mounted on the Sony A7 III camera.
The Tamron 17-28mm F2.8 Di III RXD isn't fully weather-proof but it does benefit from a moisture-resistant construction which helps to prevent moisture from penetrating the lens, although we'd hesitate to use it in the rain for a prolonged period.
The front element has a hydrophobic Fluorine Coating that is highly resistant to fingerprints and debris.
The Tamron 17-28mm lens is supplied with plastic lens caps and a plastic flower-shaped lens hood - there's no lens bag included. The filter size is 67mm.
At the 17mm focal length the angle of view is 103°41'
At the 28mm focal length the angle of view is 75°23'.
Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are very well controlled with the Tamron 17-28mm F2.8 Di III RXD lens - the example below shows the typical worst-case scenario.
With the Tamron 17-28mm F2.8 Di III RXD wide open at f/2.8, you can see some noticeable light fall-off in the corners. Stopping down helps, although to completely get rid of this phenomenon, you will need to use an f-stop of f/5.6 or smaller. There's also noticeable barrel distortion at the 17mm focal length.
Vignetting at 17mm
Vignetting at 28mm
The Tamron 17-28mm F2.8 Di III RXD isn't claimed to be a macro lens, but it delivers pretty good performance nonetheless if you zoom to 28mm. The close-focus point is an impressive 19cm from the film/sensor plane at the 17mm focal length (26cm at 28mm) and it has a maximum magnification ratio of 1:5.2 at the 17mm focal length (1:6 at 28mm).
Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc. One of the reason to buy such a fast lens as the Tamron 17-28mm F2.8 Di III RXD is to be able to isolate the subject from the background. Tamron was apparently very much aware of this requirement, as they employed an iris diaphragm with nine rounded blades for a pleasing rendering of the out-of-focus highlights. Based on what we have seen, we can say that they largely succeeded. Below you'll find some examples, but you are also encouraged to check out our sample images.
In order to show you how sharp this lens is, we are providing 100% crops on the following pages.