Samyang 10mm F2.8 ED AS NCS CS

Sharpness

Sharpness is one of the key advantages of prime lenses over zooms.  Does the Samyang 10mm F2.8 deliver in this respect?

In order to test the sharpness of the lens, we took a number of studio and outdoor tests, focusing on the center, edge, and corner of each image.  All tests on this page were shot with the Pentax K-5 IIs.

Outdoor Test Scene

Full-size crops of parts of the above image at various aperture settings follow.

Center

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

These results are conclusive.  Sharpness is good wide-open (though there's less contrast), very good at F3.5 and F4, and exceptional from F4.5 through F8.  Diffraction sets in at F11 and considerably degrades the image at F16 and higher.  For the best results at F2.8, we recommend applying an unsharp mask to your out-of-camera images.

Edge

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

The edge sharpness from this lens is excellent.  We see a similar trend as in the center of the frame: wider apertures are sharp while smaller apertures suffer due to diffraction.

Note the slight variation in exposure due to vignetting (first 3 photos) and overexposure at F22 (last photo).

Corner

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

The corners follow a similar pattern, with sharpness peaking between F4.5 and F5.6 before taking a bit hit at F13.5 and above.  This degree of sharpness in the corners is remarkable.

Test Chart - Center

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

These charts were taken at a distance of approximately 1.5 meters, and the images above are full-size crops.

The lens is at its sharpest at F4.5, with F5.6 coming in a very close second.  Our studio findings agree with our real-world tests: apertures between F3.5 and F8 can safely be used on a daily basis with this lens, though the test charts do offer us a bit more insight into the effects of diffraction at F9.5 and higher.  F2.8 is better than F9.5, but it does lack a little bit of contrast.

Test Chart - Edge

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

Our studio edge test shows us that edge sharpness isn't quite as good as center sharpness, but our real-world findings still stand.

Test Chart - Corner

F2.8
F3.5
F4
F4.5
F5.6
F6.7
F8
F9.5
F11
F13.5
F16
F19
F22

Like in the center, corner sharpness peaks at F4.5, but again, the corners aren't quite as sharp as the center of the frame, as is to be expected.  Still, the Samyang 10mm passed our tests with flying colors.

Full-size Samples

If you'd like to just the 10mm's sharpness on your own, click on any thumbnail below for a full-size image download.

F2.8		F4
F5.6		F8

Verdict

For a lens this wide, it's hard to ask for more in terms of sharpness.  Just stop down to F4 and F4.5 and the Samyang 10mm F2.8 will deliver exceptionally-sharp centers, edges, and corners.  The lens is also quite good wide-open.  The only aperture settings to avoid are F11 and smaller, due to diffraction.

Indeed, distant details will appear very small when shot with the 10mm, but what you do see will be sharp!