LensTip.com

It would be difficult to find any direct rivals of the tested Tamron because no other producer has presented a lens with such an aperture fastness and focal length range so far. In our chart we decided to stack it up against other APS-C lenses which focal lengths start around 16-17 mm and end at 70-80 mm and apertures are faster, even if only momentarily, than fixed f/4.0.

Keeping the aperture of the Tamron in mind, you won't be especially surprised that physically it is the heaviest and the biggest lens in this group. What's interesting, its filter thread is hardly the biggest, and also its minimum focusing distance sticks out in a positive way.

In the photo below the Tamron 17-70 mm f/2.8 Di III-A VC RXD is positioned next to the Olympus M.Zuiko 12–40 mm f/2.8, also a very universal instrument, with a fixed f/2.8 aperture.

Please Support Us If you enjoy our reviews and articles, and you want us to continue our work please, support our website by donating through PayPal. The funds are going to be used for paying our editorial team, renting servers, and equipping our testing studio; only that way we will be able to continue providing you interesting content for free.

- - - - - - - - - - - - - - - - - advertisement - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The tested lens starts with a metal mount with contacts and a 32x23 mm frame. Inside that frame you find a rear element, 26 mm in diameter; it doesn't move and is hidden half a centimeter inside the frame. The area around it is properly blackened and very well matted – from this side the lens looks very well and seems to be weather-sealed.

The proper body of the lens is covered by black plastic; it starts with an immobile, smooth ring on which you see a silver stripe and a mark to ease an alignment with a camera. The ring increases its diameter very fast and on its enlargened part you find an inscription with the name and parameters of the lens, along with information that the lens was designed in Japan but produced in Vietnam.

The next part is a manlual focus ring, 13 mm wide, completely covered by ribs. It comes without any distance and/or depth of field scale. The ring, a focus-by-wire construction, moves very smoothly and is properly damped. Even if you turn it faster the focus throw amounts to an angle of over 180 degree ensuring great precision of your settings.

Further on you see a smooth part of the barrel as wide as 9mm. It doesn't move and behind it starts a zoom ring, 40 mm wide, most of its surface covered by rubber ribbing. The ring also features focal length markings at 17, 24, 35, 50, and 70 mm.

If you turn this ring going from 17 to 70 mm focal length, a uniform, plastic tube pulls out of the barrel, ending with a front element system. During that operation the size of the lens increases by 29 mm.

The front element is 56 mm in diameter, surrounded by a non-rotating filter thread, 67 mm in diameter, and a hood mount.

When it comes to optical construction you deal here with 16 elements positioned in 12 groups. Producers haven't been skimpy when it comes to special elements – you get two low dispersion glass LD elements and three aspherical ones, among them two molded glass and one hybrid aspherical. Inside the construction you can also find a round aperture with nine blades which can be closed down to a value of f/22. The construction of the Tamron lens is moisture resistant and the outer surface of its front element is coated with a hydrophobic Fluorine compoud that is supposed to be also fingerprint-resistant.

Buyers get in the box with the lens: both caps, and a petal-type hood.

Image stabilization

In order to check the efficiency of vibration reduction system of the Tamron 17-70 mm we took several dozen photos at the 70 mm focal length with shutter speeds ranging from 1/125 to 1/2 of a second with the stabilization switched on and off. Then we calculated the percentage of blurred photos at every speed and presented the results as an exposure time function graph, expressed in EV (with 0 EV being the equivalent of 1/100 of a second).

The maximum distance between both curves reaches about 3.7 EV and such is, in our opinion, the efficiency of the stabilization system, featured by the tested lens. Taking into account the fact that the majority of producers declare an efficiency of about 4 EV in this class of equipment and usually that efficiency is not higher than 3.7-4.3 EV, te result reached by the Tamron should be called very sensible and we think the VC mechanism of this lens works properly well.