Tamron SP 24-70 mm f/2.8 Di VC USD
Our measurements confirm it completely. At the shortest focal length and the maximum relative aperture the light fall-off in the frame corners is just 14% (-0.42 EV) and it becomes even more imperceptible already on stopping down by 1 EV. The situation in the middle of the focal range is even better because there the vignetting is difficult to spot even with the lens wide open – it amounts to just 11% (-0.35 EV). On stopping down to f/4.0 the vignetting decreases to 8%. At 70 mm focal length the performance is very similar. The results, recorded by us by f/2.8 and f/4.0 are respectively 12% and 7%.
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You can meet with serious difficulties only on full frame – it can be noticed very clearly below.
At the combination of f/2.8 aperture and 24 mm focal length the brightness loss in the frame corners amounts to as much as 61 % (-2.70 EV). It’s worth noticing that the competitors deal much better here because the Nikkor 24-70 mm has a result of 42% and the Sigma 24-70 mm gets to 50%. Stopping down allows you to decrease the vignetting a bit but this aberration does so a bit too slowly for our tastes. By f/4.0 you still have a high value of 44% (-1.65 EV) so higher than in the case of the Nikkor at the maximum aperture! On stopping down the aperture to f/5.6 you see the vignetting reduced to the level of 32% (-1.11 EV) but further stopping down won’t help much because by f/8 we get the result of 30% and by f/11 – just 1% lower.
In the middle of the focal range at the maximum relative aperture the vignetting reaches 49 % (-1.95 EV). Once again this performance is worse than that of the Nikkor and the Sigma. On stopping down to f/4.0 we can reduce that aberration to the value of 30% (-1.05 EV) and implementing f/5.6 aperture gives a result of 21% (-0.67). This aberration remains noticeable by f/8 and f/11 where it reaches near 17% (0.55 EV).
At the maximum focal length and maximum relative aperture the light fall-off in the corners of the frame gets to 55% (-2.31 EV). Once again it is a result much worse than in the case of the tested lens’s competitors (the Sigma had 43% here and the Nikkor – 38%). On stopping down to f/4.0 you see the vignetting drop to the value of 35% (-1.23 EV) and using f/5.6 aperture reduces it to the level of 25% (-0.83 EV). This aberration remains still visible by f/8 and f/11 where it reaches respectively 18% and 13%.