Full review
Tamron’s latest zoom lens covers the popular 24-70mm focal length span with a fast maximum aperture that remains at f/2.8 throughout the range. The SP 24-70mm f/2.8 Di VC USD is designed primarily for cameras with 36 x 24 mm sensors but, being a ‘Di’ lens, it is usable with APS-C camera bodies.
Side view of the SP 24-70mm f/2.8 Di VC USD lens. (Source: Tamron.)
Canon, Nikon and Sigma offer 24-70mm f/2.8 lenses but they’re not stabilised. Sony’sCarl Zeiss 24-70mm f/2.8 lens isn’t stabilised, either, but sensor-shift stabilisation is included in its camera bodies. The table below compares key features of the lenses.
| Tamron | Canon | Nikon | Sony | Sigma | |
| Lens construction | 17 elements in 12 groups | 18 elements in 13 groups | 15 elements in 11 groups | 17 elements in 13 groups | 14 elements in 12 groups |
| Stabilisation | Yes | No | No | No | No |
| Closest focus | 0.38 m | 0.38 m | 0.38 m | 0.34 m | 0.38 m |
| Focus drive | Ultrasonic Silent Drive | Ring USM | Silent Wave Motor | Super Sonic wave Motor | Hyper-Sonic Motor |
| Filter | 82 mm | 82mm | 77 mm | 77 mm | 82mm |
| Dimensions | 88.2 x 108.5 mm | 88.5 x 113.0 mm | 83 x 133 mm | 83 x 111mm | 86.6 x 94.7 mm |
| Weight | 825 grams | 805 grams | Approx. 900 grams | Approx. 955g | 790 grams |
| RRP (AU$) | $1399 | $2899 | $2199 | $2799 | $1349 |
Going on price alone, the Tamron lens appears to be excellent value for money. The SP 24-70mm f/2.8 Di VC USD will be offered with mounts to suit Canon, Nikon and Sony DSLRs, with the Canon model becoming available first. The Sony compatible model will lack Vibration Compensation (VC), as this functionality is already built into Sony DSLR and SLT bodies. We reviewed it on Canon’s EOS 5D Mark II.
Tamron makes no claims about the degree of compensation provided by its VC system but, given its sophistication, it should be pretty good (a judgement confirmed by our usage tests). The VC element is held in place only by contact with the ceramic balls, enabling it to compensate for vibrations in all directions.
The diagram above shows how the VC mechanism in the lens works. (Source: Tamron.)
It has three magnets which are driven by corresponding driving coils. In the control unit, two gyro sensors pick up the horizontal and vertical vibrations and report them to the micro processor, which controls the moving element.
The optical design of this lens is relatively complex, with 17 elements in 12 groups. Three LD (Low Dispersion) elements are included to minimise chromatic aberrations, while three glass-moulded aspherical lenses, one hybrid aspherical lens and two XR (Extra Refractive Index) elements optimise light transmission. The fast f/2.8 maximum aperture is maintained throughout the zoom range.
The diagram above shows the construction of the lens and indicates the positions of the exotic elements. (Source: Tamron.)
Nine iris blades close to a circular aperture. At 82 mm, the filter size is the same as the new Canon lens and the Sigma equivalent and larger than the competing models from Nikon and Sony (which, interestingly, are heavier).
Tamron’s Ultrasonic Silent Drive AF system is similar to the AF systems in its rivals, driving focusing with high-frequency ultrasonic vibrations from two ring-shaped elements. When combined, the energy from these vibrations is used to create a smooth autofocus drive and support continuous manual focusing. These systems provide fast and almost silent focusing.
Build and Ergonomics
TheSP 24-70mm f/2.8 Di VC USD is Tamron’s ï¬rst lens with moisture-resistant (but not waterproof) construction, which puts into the same class as its rivals. Build quality meets the expected high standards, as indicated by the not inconsiderable weight of this lens. However, it felt well balanced on the substantial body of the EOS 5D II we used for our tests.
Tamron doesn’t reveal what this lens is made from, although going by look and feel it’s probably polycarbonate plastic over a metal chassis. The mounting plate at the camera end is sturdy stainless steel and a thin rubber gasket around the mount excludes dust and moisture.
A bayonet mounting on the outside of the front of the lens accepts the supplied petal-shaped lens hood, which is made from black polycarbonate and also very solidly built. Just behind it is the zoom ring, which is 40 mm wide and carries a deeply-ridged rubber grip coating that is roughly 30mm wide and starts close to the front of the ring.
Focal length marks are stamped on the trailing edge of the zoom ring indicating 24mm, 35mm. 50mm and 70mm positions. A zoom lock is located on this ring, slightly to the right of the 24mm position. We didn’t need to use it during our tests as the lens showed no evidence of zoom creep, even when facing downwards.
The zoom ring moves through a quarter of a turn as you span the focal length range and the inner barrel extends approximately 30 mm at the 70mm position. The underside of this ring bears a ‘Made in Japan’ stamp.
Behind the zoom ring is a narrow strip that carries the gold band on which the name and filter diameter are stamped. The focus ring, which is 10 mm wide with a deeply-ridged rubber grip lies just aft of this strip. It turns through 360 degrees. The ring is well damped for manual focusing, which makes precise adjustments straightforward.
An inset distance scale behind the focusing ring shows distances in feet and metres from 0.38 metres (1.25 feet) to infinity. Near the back of this section of the lens barrel and around to the left hand side are two sliders. The top one switches between auto and manual focusing, while the lower one switches the image stabiliser on and off.
The front element does not rotate during focusing or zooming, allowing use of angle-critical attachments like polarisers. Attaching the supplied lens hood keeps the front element inside the hood while zooming, protecting it against stray light.
Performance
Our shooting tests were carried out with the Canon EOS 5D Mark II body, which was a good match with the lens. Autofocusing was fast, quiet and accurate and the f/2.8maximum aperture provided full scope for the high sensitivity of the camera’s AF point array.
Imatest showed the lens to be capable of matching the performance of the 5D III’s sensor. Interestingly, the Tamron lens delivered slightly higher centre resolution than the Canon 24-70mm lens we tested recently although the Canon lens provided a bit better edge resolution. The graph below shows the results of our tests with the Tamron lens.
The highest resolutions were recorded at f/5.6 for all focal lengths, with the 35mm focal length performing best. At 24mm, resolution was lower than for the other focal lengths, and the peak performance occurred around f/4. Edge softening was greater than we found with the Canon 24-70mm lens.
Lateral chromatic aberration was mostly negligible, although it ventured into the ‘low’ band at some focal length and aperture settings. In the graph of our Imatest results below, the red line marks the boundary between ‘negligible’ and ‘low’ CA, while the green line separates ‘low’ and ‘moderate’ CA.
Vignetting was quite obvious at the widest aperture settings and didn’t vanish until the lens was stopped down to around f/4. This issue may not concern many potential purchasers as it seldom shows up in normal photography unless there’s a fair amount of blue sky (or similarly even tone) in the shot.
Barrel distortion was quite obvious at 24mm, with slight pincushion distortion evident at 70mm. These distortions were uniform across the frame and, therefore, easily corrected with editing software.
Because this lens can’t focus closer than 38 cm from subjects, it’s not suitable for close-up shooting unless subjects are relatively large. The wide maximum aperture, which applies across the focal length range, provides plenty of scope for differential focusing. Bokeh was smooth and very attractive with longer focal length settings.
Thanks to its effective hood, the review lens was relatively immune to flare and ghosting, even with a bright light source just outside the field of view. However, image contrast was diminisheda little when wide lens apertures were used. Beyond f/4, full contrast was maintained.
The VC stabilisation system provided a steady viewfinder image, which was useful when shooting in low light levels. With care, we were able to use shutter speeds as slow as 1/2 second with the 24mm focal length and 1/25 second for the 70mm focal length.
In summary
Buy this lens if:
– You require a professional-quality standard zoom lens for use on DLSR cameras with ‘full-frame’ sensors.
– You want superior performance across a wide range of aperture settings with all focal lengths.
– You need the sharpness and low-light shooting potential provided by effective stabilisation.
Don’t buy this lens if:
– You need macro capabilities.
SPECS
Picture angle: 84 degrees 4 minutes to 34 degrees 21 minutes
Minimum aperture: f/22
Lens construction: 17 elements in 12 groups; includes four aspherical elements, three LD elements and two XR elements
Lens mounts: Canon, Nikon, Sony (without VC stabilisation)
Diaphragm Blades: 9 (rounded aperture)
Focus drive: Ultrasonic Silent Drive (USD)
Stabilisation: Vibration Compensation
Minimum focus:38 cm
Maximum magnification: 1:5 (at f=70mm: MFD 0.38m)
Filter size:82 mm
Dimensions (Diameter x L): 88.2 x 108.5 mm
Weight: 825 grams
RRP: AUD$1399; US$1299
TESTS
(based on JPEG files from the Canon EOS 5D Mark II)
SAMPLES
Vignetting at 24mm.
Vignetting at 70mm.
Rectilinear distortion at 24mm.
Rectilinear distortion at 70mm.
24mm focal length, ISO 200, 1/13 second at f/8.
70mm focal length, ISO 200, 1/25 second at f/8.
Strong backlighting at 24mm; ISO 200, 1/400 second at f/8.
Strong backlighting at 70mm; ISO 200, 1/1000 second at f/8.
Close-up at 24mm; ISO 200, 1/100 second at f/2.8.
Close-up at 70mm; ISO 200, 1/200 second at f/2.8.
Stabilisation; 24mm focal length, ISO 200, 1/2 second at f/11.
70mm focal length, ISO 200, 1/40 second at f/2.8.
24mm focal length, ISO 200, 1/50 second at f/3.5.
24mm focal length, ISO 200, 1/125 second at f/5.
24mm focal length, ISO 200, 1/200 second at f/6.31.
70mm focal length, ISO 200, 1/125 second at f/4.
70mm focal length, ISO 200, 1/8 second at f/8.
Rating
RRP AUD$1399; US$1299
- Build: 9.0
- Handling: 8.8
- Image quality: 9.0
- Versatility: 8.5