Lens review

Tamron SP 24-70 mm f/2.8 VC USD G2

18 December 2018
Arkadiusz Olech

4. Image resolution

The resolution test (resolution meaning MTF50 function) of the Tamron SP 24–70 mm f/2.8 VC USD G2 was based on RAW files from the Canon EOS 5D Mark III. In the case of that reflex camera the decency level is situated near 30-32 lpmm and high quality, top-of-the-range fixed focal lenses can reach a maximum level of 45-50 lpmm . Not so long ago the resolution record for that sensor belonged to the Zeiss Otus 1.4/28 (49.2 lpmm) but then it’s been slightly beaten by the Sigma A 85 mm f/1.4 DG HSM, and the Sigma A 135 mm f/1.8 DG HSM so currently it amounts to 51.6 lpmm .

Let’s check how the Tamron SP 24-70 mm f/2.8 VC USD G2 compares – its results in the frame centre at 24, 45 and 70 mm focal lengths presents the graph shown below.

Tamron SP 24-70 mm f/2.8 VC USD G2 - Image resolution

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Best values, which can be easily described as excellent, the tested lens reaches at the 24 mm focal length. In that case, even at the maximum relative aperture, it brushes against a very high level of 40 lpmm and on stopping down the aperture the lens is even able to exceed slightly 43 lpmm.

In the middle of the focal range the maximum level is also placed near 43 lpmm but at the maximum relative aperture the lens performs a bit weaker as in that place the MTFs are less than 35 lpmm. Still, the image quality at that place should be called good.

You see the weakest results at the 70 mm focal range. Here by f/2.8 they get to 32 lpmm so a tad above the decency level. On stopping down the aperture MTFs are able to exceed 40 lpmm so at that place the lens doesn’t have any problems with producing images of very high resolution.

To sum up: in the frame centre the Tamron didn’t have any weak points. How does it compare with its predecessor and rivals? The results of the older Tamron were very similar at 24 mm but near f/2.8 and at the longer end of the focal spectrum that lens was weaker, mainly because of significant spherical aberration. When it comes to the rivals, if you turn a blind eye to a bit lower resolution at 70 mm and by f/2.8, in this category the Tamron can compete on equal terms with more expensive models such as the Canon EF 24–70 mm f/2.8L II USM or the Nikkor AF-S 24–70 mm f/2.8E ED VR. The Sigma A 24–70 mm f/2.8 DG OS HSM fares a bit better than the tested lens but differences are slight, in most cases bordering the margin of error. The Tokina AT-X PRO FX SD 24–70 mm f/2.8 (IF) managed to put to shame all the rest showing that even a zoom lens can noticeably exceed 45 lpmm even at several focal lengths.

Now let’s see how the Tamron SP 24–70 mm f/2.8 VC USD G2 performs on the edge of the APS-C/DX sensor.

Tamron SP 24-70 mm f/2.8 VC USD G2 - Image resolution

In this case we have no objections whatsoever to the 24-45 mm range. Even with the lens wide open you still reach the decency level or you are close to it. On stopping down the image quality improves: the MTFs soar to 35–38 lpmm which should ensure a satisfying image quality.

Once again the 70 mm focal length is the weakest but mainly at the maximum relative aperture where images are simply soft. Stopping down the lens to near f/3.5 helps, making the problems disappear and from f/5.6 the MTFs are virtually the same for all focal lengths.

Let’s pass to the performance on the edge of full frame – appropriate graph you can find below.

Tamron SP 24-70 mm f/2.8 VC USD G2 - Image resolution

The maximum relative aperture is weak no matter what focal length you employ. Fortunately when you stop down the lens by 1–1.3 EV the problems disappear and images become useful.

At the end of this chapter, traditionally, we present crops taken from photo of our resolution testing charts, saved as JPEG files.

Canon 5D MkIII, JPEG, 24 mm, f/4.0
Tamron SP 24-70 mm f/2.8 VC USD G2 - Image resolution
Canon 5D MkIII, JPEG, 70 mm, f/2.8
Tamron SP 24-70 mm f/2.8 VC USD G2 - Image resolution