LensTip.com

Lens review

Tamron 20 mm f/2.8 Di III OSD M 1:2

27 March 2020
Maciej Latałło

7. Coma, astigmatism and bokeh

The Tamron 2.8/20 doesn't experience any problems with coma correction. Images of a diode in frame corners are just slightly enlarged when you compare them to images in the very centre. The lens should be only praised here.

Center, f/2.8 Corner APS-C, f/2.8 Corner FF, f/2.8
Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh
Center, f/4.0 Corner APS-C, f/4.0 Corner FF, f/4.0
Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh


Astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, amounted to 4.2% and we consider it to be a very low level. Also in this category the lens performs beyond reproach.


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The appearance of out-of-focus images is just decent but we don't expect anything more from a lens with such parameters. A rim and onion ring bokeh make themselves felt a bit, mainly due to aspherical elements inside the construction. You should also mention influence of mechanical vignetting which truncates ciricles even on stopping down the aperture by 2 EV.

Center, f/2.8 Corner APS-C, f/2.8 Corner FF, f/2.8
Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh
Center, f/4.0 Corner APS-C, f/4.0 Corner FF, f/4.0
Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh
Center, f/5.6 Corner APS-C, f/5.6 Corner FF, f/5.6
Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh Tamron 20 mm f/2.8 Di III OSD M 1:2 - Coma, astigmatism and bokeh