In summary
Tamron’s 20-40mm f/2.8 Di III VXD is likely to delight prospective buyers, whether they purchase it for a specific purpose like real estate photography, or just for general use. Being small and light, it’s great for street photography, while its relative lack of distortion makes it ideal for landscapes and architecture.
It’s also keenly priced to be affordable by most photo enthusiasts – and even family photographers who want to be able to capture sharp stills and videos. We seldom review lenses in which the three key criteria of size, performance and price are so favourably aligned.
Full review
Announced at the end of September, Tamron’s new 20-40mm f/2.8 Di III VXD (Model A062) provides a fast, wide-angle zoom lens for Sony’s full-frame mirrorless cameras. Its compact size and light weight make it easy to use while travelling and moisture-resistant construction plus a fluorine coating on the front element to resist water, grit and grease enable it to be used for location shooting. Near silent operation enables it to be used for recording video as well as shooting stills.
Angled view of the new Tamron 20-40mm f/2.8 Di II VXD lens. (Source: Tamron.)
The optical design of this lens is quite complex, comprising 12 elements in 11 groups. Included in the design are four LD (Low Dispersion), two GM (Glass Moulded Aspherical) and one Hybrid Aspherical lens elements, which combine to address common aberrations, as shown in the diagram below.
The optical design of the Tamron 20-40mm f/2.8 Di II VXD lens showing the positions of the exotic elements. (Source: Tamron.)
Tamron’s BBAR-G2 (Broad-Band Anti-Reflection Generation 2) Coating has been applied to mimimise ghosting and flare and allow images to be reproduced with optimal contrast and clarity. A nine-bladed iris diaphragm delivers a creamy, beautiful bokeh at wide apertures, as users expect from fast lenses.
Autofocusing is driven by a Tamron-designed VXD (Voice-coil eXtreme-torque Drive) linear motor mechanism, which uses voice-coil motors. It’s fast and quiet and capable of pinpoint accuracy as well as excellent focus tracking performance when shooting video.
The close-up shooting extends from an approximate quarter life-size reproduction ratio at the minimum focus of 17 cm with the 20mm focal length to about 1/5 life size at 40mm where the minimum focus is 29 cm. Neither fits into the ‘macro’ category but both would be suitable for photos of larger flowers and small animals, particularly with location shots.
The lens is also compatible with Sony-specific functions like Eye AF, Fast-Hybrid AF and in-camera lens corrections for vignetting, chromatic aberration and distortion. It also supports Direct Manual Focus (DMF) in AF mode. It is also compatible with the dedicated Tamron Lens Utility software that enables users to customise focus ring settings and install firmware updates when they are released.
The lens is supplied with a petal-shaped lens hood and front and rear caps.
Who’s it For?
The wide angle coverage with minimal distortion makes this lens a ‘dream lens’ for real estate photographers. It’s also a good choice for owners of Sony Alpha full-frame cameras who want to shoot everything from expansive landscapes and cityscapes to family snapshots and street photography.
It is compact and light enough for travellers and also for mounting on a gimbal for handheld use while vlogging as well as a good choice for family videos and recording events for posting online. The fast, constant f/2.8 maximum aperture also makes it ideal for indoor shooting, where the 20mm focal length will allow it to be used in tight settings.
The 20-40mm lens uses the same 67mm filter size as most other Tamron lenses for Sony’s full frame mirrorless cameras and is compatible with many camera-specific features and functions, including Fast Hybrid AF and Eye AF. Although designed for a 36 x 24 mm sensor, it can be used on a cropped sensor camera, where it covers the full-frame equivalent range of 30-60mm.
Build and Ergonomics
Tamron doesn’t specify the materials used in the construction of this lens but, going on its similarity to other Tamron lenses we’ve reviewed recently, we’d say the outer and inner barrels are made mostly of composite polycarbonate on a metal mount. Build quality is very sound and up to the company’s usual high standard.
The surfaces have a similar gloss to other models with good resistance to abrasion and fingerprints. Grip performance benefits from the increased density of the ridges on the rubber-clad rings.
The focusing ring, which is located 13 mm back from the front of the lens, is approximately 13 mm wide and has finer ridging than the zoom ring. Since focusing is driven from the camera, this ring turns through 360 degrees when power is not supplied.
Behind the focusing ring is a 7 mm wide inwardly-curved section of the barrel, which carries the white index mark for aligning the zoom ring. The zoom ring is 22 mm wide and mostly covered in rubber ridging that is thicker than the focusing ring’s to make it identifiable by touch.
The front four millimetres is not ridged but carries markings for focal length settings for 20mm, 24mm, 28mm 35mm and 40mm focal lengths. The inner barrel extends by almost 10 mm without changing its orientation when you zoom from 40mm to 20mm. Zooming is smooth and positive with no slack and the internal adjustments ensure hassle-free use of angle-critical filters and other attachments.
Behind the zoom ring is a 12 mm wide band that carries the lens data (Name and serial number) plus ‘Designed in Japan’.) The barrel slopes inwards for another 7 mm and this section contains the USB Type C socket for connecting the lens to a computer.
Aft of this band is another 2 mm wide band that ends in a silver branding ring. In front of it is a ‘Made in Vietnam’ label plus a range of CE icons. The lens ends in a solid metal mounting plate with a bayonet fitting for E-mount cameras plus 10 electronic contacts inside the fitting for passing data between the camera and the lens.
Performance
Our Imatest tests showed the review lens to be an excellent performer with the best measured performance measured in the centre of the frame at the 24mm focal length with an aperture of f/3.5. As expected, resolution declined towards the edges of the frame, although not nearly as much as we’ve measured with many wide angle lenses we’ve tested.
In this graph of the Imatest measurements for JPEG files, the red line marks the approximate position at which resolution begins to exceed the expected level for the testing camera’s sensor.
We were particularly impressed by how much the resolution for JPEG files exceeded expectations for the 24-megapixel camera we used for our tests. The red line in the graph above shows the approximate value at which the expectations for the 24-megapixel sensor are surpassed. It’s worth noting that this happens with all focal lengths and across a wide range of aperture settings, particularly in the shorter focal lengths.
Resolution was significantly higher for ARW.RAW files, which also recorded a noticeably wider dynamic range. This difference was measurable across all aperture and focal length settings and from the centre of the frame to the periphery, which is to be expected.
Our lateral chromatic aberration measurements are based on ARW.RAW files from the Sony α7 II camera we used for our tests. This is because the camera provides internal corrections for JPEGs, and even though we disabled them there appears to be a residual effect in JPEG files.
The graph of our test results above shows this aberration is not a serious issue for users since even uncorrected raw files showed chromatic aberration to be well within the ‘low’ CA band, the boundary of which is indicated by the vertical red line. CA correction is included in most cameras and raw file converters.
Thanks to the supplied lens hood it was difficult to force the lens to flare, although we found some minor flare artefacts in our sunstars test shots. No veiling flare was detected, even with strong backlighting and when a bright light source was just outside the frame. Bokeh was as smooth and attractive as we expected from such a fast wide angle zoom lens.
Autofocusing was generally fast and accurate, even with moving subjects and in widely different lighting conditions. It was also virtually silent, enabling this lens to be used for recording videos.
Both vignetting and rectilinear distortion had to be assessed through ARW.RAW files with all optical and profile corrections disabled in Adobe Camera Raw. We found slight vignetting at the widest apertures across all focal lengths.
It was a little more obvious at 20mm with the maximum aperture of f/2.8 but across the entire focal length range was gone by f/3.5. Enabling the optical corrections eliminated most vignetting and the problem is easily corrected when raw files are converted into editable formats.
Slight barrel distortion could be seen at all focal lengths but it was most noticeable at 20mm and 24mm barely visible at 40mm. Both vignetting and rectilinear distortions are largely irrelevant since they are corrected automatically in JPEGs and most raw file converters.
Conclusion
Please Login or Register to access the Conclusion.
SPECS
Picture angle: 94 degrees 30 minutes to 56 degrees 49 minutes
Minimum aperture: f/22
Lens construction: 12 elements in 11 groups (including 4 LD, 2 GM aspherical and one Hybrid Aspherical elements plus BBAR-G2 anti-reflection coating and fluorine coating on front element)
Lens mount: Sony E
Diaphragm Blades: 9 (rounded aperture)
Weather resistance: Moisture-Resistant Construction
Focus drive: VXD (Voice-coil eXtreme-torque Drive) linear motor
Stabilisation: Relies on in-camera IS in Sony cameras
Minimum focus: 17 cm at 20mm; 29 cm at 40mm
Maximum magnification: 1:3.8 at 20mm; 1:5,1 at 40mm
Filter size: 67 mm
Dimensions (Diameter x L): 74.4 x 86.5 mm
Weight: 365 grams
Standard Accessories: Front and end caps, petal-shaped lens hood
Distributor: Blonde Robot, (03) 9023 9777
TESTS
Based upon JPEG files taken with the Sony α7 II camera.
Based on ARW.RAW files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.
SAMPLES
Vignetting at 20mm f/2.8.
Vignetting at 24mm f/2.8.
Vignetting at 28mm f/2.8.
Vignetting at 35mm f/2.8.
Vignetting at 40mm f/2.8.
Rectilinear distortion at 20mm.
Rectilinear distortion at 24mm.
Rectilinear distortion at 28mm.
Rectilinear distortion at 35mm.
Rectilinear distortion at 40mm.
20mm focal length, ISO 100, 1/500 second at f/9.
40mm focal length, ISO 100, 1/500 second at f/9.
20mm focal length, ISO 800, 1/13 second at f/11.
Crop from the corner of the above image at 100% magnification showing distorted highlights and loss of sharpness.
Crop from the edge of the above image at 100% magnification showing no coloured fringing.
40mm focal length, ISO 800, 1/15 second at f/11.
Crop from the edge of the above image at 100% magnification showing no coloured fringing.
Close-up at 20mm f/2.8; ISO 200, 1/200 second.
Close-up at 40mm f/2.8; ISO 200, 1/200 second.
Sunstar at 20mm f/22; ISO 100. 1/125 second.
Sunstar at 28mm f/22; ISO 100. 1/250 second.
Sunstar at 35mm f/22; ISO 100. 1/100 second.
Sunstar at 40mm f/22; ISO 100. 1/160 second. Note the minor flare artefacts.
Backlighting; 20mm focal length, ISO 100. 1/125 second at f/8.
20mm focal length, ISO 200. 1/160 second at f/7.1.
20mm focal length, ISO 200. 1/400 second at f/8.
40mm focal length, ISO 100. 1/320 second at f/9.
20mm focal length, ISO 100. 1/80 second at f/6.3.
20mm focal length, ISO 100. 1/125 second at f/7.1.
40mm focal length, ISO 100. 1/400 second at f/9.
20mm focal length, ISO 100. 1/80 second at f/5.6.
20mm focal length, ISO 100. 1/80 second at f/5.
20mm focal length, ISO 100. 1/160 second at f/9.
32mm focal length, ISO 100. 1/160 second at f/9.
20mm focal length, ISO 100. 1/160 second at f/8.
20mm focal length, ISO 100. 1/160 second at f/9.
Rating
RRP: AU$1299; US$699
- Build: 9.0
- Handling: 9.0
- Image quality: 9.1
- Autofocusing: 9.0
- Versatility: 8.7
BUY