TAMRON SP 24-70MM F2.8 DI VC USD G2
Following the 70-200mm model, Tamron gives its SP series 24-70mm f2.8 the G2 upgrade to give both Canon and Nikon D-SLR users a highly competitive alternative.
Tamron’s revival continues with its latest ‘Generation 2’ upgrade of an SP series lens, this time the 24-70mm f2.8 zoom which, like its 70200mm f2.8 stablemate, presents a creditable alternative to the camera brand models.
They must be putting something in the water over at Tamron at the moment. After a long period when great rival Sigma was making all the running, it’s now hard to keep up with the steady stream of new lenses from Tamron – both fresh designs such as the 18-400mm superzoom for ‘APS-C’ sensors, and the on-going ‘Generation 2’ program of upgrades models.
We’ve already seen the G2 version of the SP series 70-200mm f2.8 telezoom – which compared very favourably with Nikon’s third-gen version of its AF-S 70-200mm f2.8 – and now it’s joined by the companion G2 24-70mm f2.8, similarly upgraded both inside and out.
The new lens’s full model designation of ‘SP 24-70mm f2.8 Di VC USD G2’ provides some clues to what’s changed which, in reality, is pretty much everything except the focal range and maximum aperture. ‘Di’ is Tamron’s indicator for its lenses designed for imaging onto full-35mm format sensors (as opposed to ‘Di II’ for the ‘APS-C’ format models), but ‘VC’ is more interesting because it stands for ‘Vibration Compensation’. which is Tamron’s optical image stabilisation system. Stabilisation was once generally only installed in longer focal length lenses because they inherently have more issues with camera shake, but Tamron puts its VC units in many shorter zooms where, in reality, they can be equally advantageous when shooting hand-held. Short focal length lenses are still used in low light situations, right? The previous model was also stabilised – the first in this class, actually – but the G2 version is now controlled by a more advanced microprocessor which enables up to five stops of correction for camera shake. This means you can go as slow – in terms of shutter speeds – as is practicably possible, making full use of the f2.8 maximum aperture when shooting at dawn or dusk, indoors or even with some night scenes. Additionally, the new system automatically switches between normal and panning modes, based on analysis of the camera movement.
A second high-powered micro-processor is tasked with autofocusing duties – that’s the ‘USD’ initials in the model number – providing faster and more accurate control of the drive system which, as is now the case on most higher-end AF lenses, uses ultrasonic pulses.
Like the companion SP 70200mm f2.8, the G2 24-70mm f2.8 has a weather-sealed barrel construction with a fluorine coating on the front element’s exposed surface to help repel dust and moisture. The main tubes are metal alloy and, at 900 grams, this lens feels pretty substantial in the hand.
On the inside, the optical construction comprises 17 elements in 12 groups, of which a total of nine are special types. This is where lens design has made significant advances over recent years and why the G2 lens is guaranteed to outperform
its predecessor. Four of the special elements are aspherical types – three made from glassmoulding and one using the hybrid technique which uses a spherical glass core over which is coated optical resin to shape the surfaces – and these work together to correct for distortion. Five of the special elements either have low dispersion characteristics or a high refractive index, which collectively ensure all the wavelengths of visible light travel through the lens in the same way in order to minimise chromatic aberrations – both axial and transverse – and spherical aberrations. Two of Tamron’s multicoating technologies – ‘eBAND’ and ‘BBAR’ – are employed to minimise internal reflections (including those coming off the sensor’s surface) and also reduce both ghosting and flare. A bayonetfit hood is supplied to further help with preventing the latter and, incidentally, employs a new locking mechanism so it’s harder to accidentally knock it off.
The minimum focusing distance is 38 centimetres which, at 70mm, gives a maximum magnification ratio of 1:5. The diaphragm has nine blades to give a more rounded aperture and hence smoother out-of-focus effects. It’s electromagnetically controlled in both mount versions – Canon EF and Nikon (G type AF) – which means, for users of the latter’s D-SLRs, that aperture setting has to be possible from the camera body.
Tamron’s G2 lenses have much more contemporary styling with flush-fitting control rings and a satin finish. It’s probably no coincidence that there’s a hint of Sigma’s Art lenses in the appearance of the new 24-70mm f2.8, particularly the inset metal ‘SP’ badge on the side of the barrel (similar to the Sigma’s ‘A’). The build quality and finish are certainly comparable.
The zooming collar has a locking switch while the focusing collar provides a full-time AF override which engages immediately that it’s turned. Both are nicely weighted, although the latter is a ‘fly-by-wire’ electronic control. A binnacle ahead of the lens mount carries AF/MF and VC ON/OFF switches.
By happy coincidence, Nikon’s D850 arrived for testing while we still had the G2 24-70mm f2.8, so it was the perfect opportunity to try it out with this camera’s 47.5 megapixels sensor and its high-performance AF system. The two got on very well indeed. The autofocusing was as fast and as reliable as with the current AF-S Nikkor 24-70mm f2.8E ED VR, which is both significantly bigger (particularly in length), heavier and more expensive. The contribution of all those special elements is very evident in the image quality, particularly the uniformity of sharpness across the frame, regardless of the focal length and across the aperture range to f16 (at f22 diffraction takes the edge off the definition). Overall though, this lens clearly doesn’t have any issues dealing with ultra-high sensor resolutions. Uniformity of brightness is also very good, and although some vignetting occurs when shooting at f2.8, it’s a lot less than is often the case, and is eliminated by stopping down to f4.0. Distortion is mostly well controlled albeit with some barreltype bending evident at 24mm and very slight pin-cushioning at around the 50mm mark. The barrel distortion is actually a bit more pronounced than we would have expected, but obviously can be easily corrected postcamera. Chromatic aberrations are virtually non-existent even in contrasty situations when shooting wide-open, and this is a key area where the new optical design is superior to both the preceding lens and a number of competitors.
Tamron’s G2 70-200mm f2.8 puts it firmly back in the game in that category of staple ‘workhorse’ zoom, and the G2 24-70mm f2.8 is similarly a serious competitor to the key rival models from Canon, Nikon and Sigma.
What Tamron’s new contender has going for it is the extended capabilities of its image stabilisation, good close-up capabilities, high-end build quality, excellent overall performance and, in the light of this, great value for money. The one niggle is the amount of barrel distortion at 24mm, but it’s still comparatively small and so won’t be an issue for many users. Tamron continues to go from strength to strength.
STABILISATION WAS ONCE GENERALLY ONLY INSTALLED IN LONGER FOCAL LENGTH LENSES, BUT TAMRON PUTS ITS VC UNITS IN MANY SHORTER ZOOMS WHERE, IN REALITY, THEY CAN BE EQUALLY ADVANTAGEOUS WHEN SHOOTING HAND-HELD.
TAMRON SP 24-70mm f2.8 DI VC USD G2 ZOOM
Large-diameter front element has a fluorine coating on its exposed surface to help repel dust and moisture, and allow for easier cleaning.
Barrel-mounted switches engage the VC image stabilisation (which has automatic mode selection) and select the focusing mode.
Lens barrel tubes are now metal alloy with a smart satin finish. Manual focusing collar provides a full-time AF override.
Weather-proofing measures include a substantial rubber gasket around the lens mount.