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Lens review

Tamron 17-70 mm f/2.8 Di III-A VC RXD

25 February 2022
Maciej Lata││o

7. Coma, astigmatism and bokeh

The Tamron 17–70ámm f/2.8 Di III-A VCáRXD corrects coma very well – images of a diode aren't deformed in the frame corner, the only thing you might notice is a slight magnification of the image itself. In this category the lens's performance should be assessed very high.

A7R III, 17ámm, f/2.8, center A7R III, 17ámm, f/2.8, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh
A7R III, 30ámm, f/2.8, center A7R III, 30ámm, f/2.8, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh
A7R III, 50ámm, f/2.8, center A7R III, 50ámm, f/2.8, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh
A7R III, 70ámm, f/2.8, center A7R III, 70ámm, f/2.8, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh


When it comes to astigmatism, understood as an average difference between horizontal and vertical MTF50 values, it amounted to 6.6%. It's a moderate value, not giving you any reason to worry. Of course you should mention the fact that it is a medium value, averaged out for all focal lengths near the maximum relative aperture. If you start to analize it in depth you can indicate that most of the problems you might encouter at 17-30 mm focal lengths, where this aberration reaches an average level of 11.2%; at longer focal lengths it is negligible, amounting to just 2.1%.


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Out-of-focus images provided by the Tamron 17-10 mm are weak. Circles feature distinct concentric rings (as many as three aspherical elements clearly make themselves felt) and are full of local extreme points. The fact that there are no serious problems with mechanical vignetting, which makes itself felt only at the maximum relative aperture, seems to be the only consolation.

A7R III, 70ámm, f/2.8, center A7R III, 70ámm, f/2.8, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh
A7R III, 70ámm, f/4.0, center A7R III, 70ámm, f/4.0, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh
A7R III, 70ámm, f/5.6, center A7R III, 70ámm, f/5.6, Corner
Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh Tamron 17-70 mm f/2.8 Di III-A VC RXD - Coma, astigmatism and bokeh