Tamron 20-40mm F/2.8 Di III VXD Review
Launched in September 2022, the Tamron 20-40mm F/2.8 Di III VXD is a fast ultra-wide-angle to standard zoom lens with a constant F2.8 aperture throughout the focal range.
This Tamron lens is designed for Sony's range of Alpha 35mm full-frame mirrorless cameras.
You can also use can use it on a smaller APS-C body like the Sony A6000 series of cameras, where the equivalent focal length will change to 30-60mm.
The Tamron 20-40mm for Sony features 11 elements in 12 groups including four LD (Low Dispersion), two GM (Glass Molded Aspherical) and one hybrid aspherical lens elements.
It has a rounded 9 blade diaphragm which creates an attractive blur to the out-of-focus areas of the image.
The Tamron 20-40mm incorporates a VXD (Voice-coil eXtreme-torque Drive) linear autofocus motor that delivers fast and quiet auto-focusing.
It offers an impressively close 0.17m minimum focusing distance and a maximum magnification of 1:3.8.
This lens has a moisture-resistant construction and a fluorine coating to protect against dust, dirt, and smearing.
The Tamron 20-40mm F/2.8 Di III VXD lens is priced at around £879 / $699 in the UK and the US, respectively.
Ease of Use
Weighing in at 365g and measuring just over 8.6cm in length, the Tamron 20-40mm F/2.8 Di III VXD is a very compact and lightweight lens considering the fast maximum aperture and the versatile wide-angle to normal zoom range that it offers.
Focusing is fully internal but zooming is not, with the length of the lens changing as you zoom from 40mm to 20mm, gradually extending further by 1cm as you move through the range.
As with most other recent Tamron lenses that we've reviewed, build quality is good. The Tamron 20-40mm for Sony feels solid enough in your hand, despite its mostly high-grade plastic construction.
It has a glossy, shiny black finish, a pattern on the focus and zoom rings, and a scratch and fingerprint resistant exterior.
There is a metal lens mount and it accepts 67mm filters. It benefits from a moisture-resistant construction which helps to prevent moisture from penetrating the lens, although we'd hesitate to use it in heavy rain for a prolonged period.
The Tamron 20-40mm F/2.8 Di III VXD has a fairly narrow, ridged focus ring. Manual focusing is only possible by delving into the menu system - there's no dedicated AF/MF switch to toggle between AF and MF on this lens.
The zoom ring is smooth and well-balanced, but the manual focus ring isn't particularly well-damped and and therefore feels light in use.
There are also no hard stops at the ends of the focal range, making it harder to set focus at infinity. Polariser users should be pleased that the 67mm filter thread doesn't rotate on focus.
The Tamron 20-40mm for Sony zoom lens utilizes a VXD (Voice-coil eXtreme-torque Drive) linear autofocus motor for fast and quiet auto-focusing.
It proved to be a very quick performer on the Sony A7R IV camera that we tested it with, and we hardly experienced any "hunting" either in good or bad light, with the lens accurately focusing virtually all of the time.
It is also almost completely silent when auto-focusing, making it perfect for movie shooting or for more candid use.
Importantly, the lens is 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.
The Tamron 20-40mm F/2.8 Di III VXD doesn't feature optical image stabilisation, so you'll have to rely on the camera body's own built-in stabilisation system (if it has one).
The USB-C Connector Port allows you to update and customise the lens directly using the TAMRON Lens Utility software, rather than via a camera body.
We are a little concerned that this port is uncovered, although Tamron state that it is fully water-proofed and therefore that a cover is not necessary.
In the customisation, the direction and speed of focus can be changed. The focus ring can be used for aperture instead of manual focusing, while the focus hold button can be customised for preset focus points 1 and 2 for video so that you can pull focus from one to the other at a designated speed.
The Tamron 20-40mm for Sony lens is designed in Japan and made in Vietnam.
It's supplied with with plastic lens caps and a good quality plastic petal-shaped lens hood (HA062), but not with a bag or case.
At the 20mm focal length the angle of view is 94°30'.
At the 20mm focal length the angle of view is 56°49'.
Chromatic aberrations, typically seen as blue or purple fringes along contrasty edges, were not too apparent in our test shots, only appearing in high contrast areas.
With the lens set to its maximum aperture of f/2.8, there's some significant light fall-off in the corners, requiring you to stop down by at least 3 f-stops to completely prevent it.
This lens suffers from some very obvious barrel distortion at 20mm and equally obvious pincushion distortion at 40mm.
Sunstars and Flare
The Tamron 28-75mm F2.8 Di III VXD G2 produces very nice sunstars when stopped-down to f/22, as shown below, and flare is well controlled even when shooting directly into the sun.
The Tamron 20-40mm F/2.8 Di III VXD offers a minimum focusing distance of 0.17m /6.7in with a maximum magnification of 1:3.8, when set to the 20mm focal length, which makes it surprisingly useful for close-ups.
At the 40mm focal length the minimum focusing distance is 0.29m /11.4in with a maximum magnification of 1:5.1.