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Lens review

Tamron 28-75 mm f/2.8 Di III RXD

26 August 2019
Maciej Lata││o

8. Vignetting

First let's check how the Tamron 28–75ámm f/2.8áFE fares on the APS-C sensor – appropriate thumbnails you can find below.

A7R II, APS-C, 28ámm, f/2.8 A7R II, APS-C, 28ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
A7R II, APS-C, 50ámm, f/2.8 A7R II, APS-C, 50ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
A7R II, APS-C, 75ámm, f/2.8 A7R II, APS-C, 75ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting


At the 28 mm focal length the vignetting is difficult to perceive even at the maximum relative aperture as it amounts to 14% (−0.42 EV); then it decreases to 8% (−0.25 EV) on stopping down the aperture to f/4.0.

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At 50 mm the situation is even better – by f/2.8 the vignetting reaches just 12% (−0.37 EV), and by f/4.0 it decreases to a value of 6% (−0.18 EV).

In the case of the APS-C sensor you get the biggest chances to see vignetting at the maximum relative aperture where, by f/2.8, it amounts to 19% (−0.62 EV). The aberration disappears practically completely by f/4.0 where the result, measured by us, amounted to just 6% (−0.19 EV).

Now let's see how the tested lens perform on the full frame detector – below you can find appropriate photos.

A7R II, FF, 28ámm, f/2.8 A7R II, FF, 28ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
A7R II, FF, 50ámm, f/2.8 A7R II, FF, 50ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
A7R II, FF, 75ámm, f/2.8 A7R II, FF, 75ámm, f/4.0
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting Tamron 28-75 mm f/2.8 Di III RXD - Vignetting


At the combination of 28 mm focal length and f/2.8 aperture you can notice very serious problems - the light fall-off amounts to as much as 66% (−3.08 EV). Stopping down the aperture helps to decrease that value but that process is hardly fast: by f/4.0 vignetting is 52% (−2.13 EV), by f/5.6 it reaches 37% (−1.33 EV), by f/8.0 it approaches 25% (−0.84 EV), and by f/11 it finally decreases to a level of 21% (−0.69 EV).

Markedly better performance can be observed at the 50 mm focal length where, at the maximum relative aperture, the vignetting is 38% (−1.40 EV); by f/4.0 it decreases to 23% (−0.76 EV), by f/5.6 it reaches 15% (−0.47 EV), and further stopping down manages to lower it by another 1%.

At the maximum focal length serious vignetting problems return. In that place by f/2.8 that aberration reaches a huge value of 63% (−2.91 EV). By f/4.0 it decreases to 46% (−1.80 EV), by f/5.6 to 29% (−0.98 EV), by f/8.0 it is 21% (−0.70 EV), and by f/11 it amounts to just 15% (−0.48 EV).

We have to say the performance in this category is really weak. It is perhaps a result of a narrow casing of the lens and a short distance dividing the rear element and the sensor. It's enough to remind here that the Tamron SP 24–70 mm f/2.8 VC USD G2, an instrument more difficult to correct in the category of vignetting just because of its wider angle of view with the same aperture fastness, fared distinctly better.

Sony A7RáII, 28ámm, f/2.8
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
Sony A7RáII, 50ámm, f/2.8
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting
Sony A7RáII, 75ámm, f/2.8
Tamron 28-75 mm f/2.8 Di III RXD - Vignetting