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Lens review

Tamron SP 24-70 mm f/2.8 Di VC USD

23 June 2012
Szymon Starczewski

6. Distortion

When you work on a small APS-C/DX sensor the distortion shouldn’t be a big problem. Its highest level (in the form of noticeably ‘barrel’ images) we notice at the shortest focal length, amounting there to -2.47%. Passing to the 35 mm can reduce it to a not very bothersome value of -0.59%. The deformations zero each other for the middle of the focal length (the official distortion value being there 0.06%) then they change the sign and, at 70 mm become ‘pincushion’ of 0.46%.

On full frame the situation you deal with is much more serious and complicated. One glance at photos below and you see that at the widest angle of view the distortion level is not only significant but also it turns into its ‘moustache’ variety. Averaged value across the frame gets to -4.78 %. If you choose only an area being more or less the equivalent of the APS-H class of sensor the distortion will already be as high as -5.60%. Both these values are high and they make the tested Tamron compare unfavourably with its rivals. It’s enough to mention here that the Nikkor at 24 mm showed the distortion level of -3.94% and the Sigma had a bit worse result of -4.59%.

After passing to 35 mm focal length the moustache distortion disappears and we deal again with classic ‘barrel’ amounting to -1.12%. In the middle of the focal range the distortion level is zeroed (0.18%) and it turns into pincushion - at 70 mm we get a result reaching 1.05%.

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50D, 24 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion
50D, 45 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion
50D, 70 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion

1Ds MkIII, 24 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion
1Ds MkIII, 45 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion
1Ds MkIII, 70 mm
Tamron SP 24-70 mm f/2.8 Di VC USD - Distortion