Sharpness at 100mm

The sharpness tests for this review were carried out using a real-world subject rather than a test chart. The Tamron 28-300mm f/3.5-6.3 Di VC PZD lens was attached to a Canon EOS 5D Mark III body, which in turn was mounted on a sturdy tripod. Self-timer mode was activated. Slight tonal changes are due to slight changes in natural light during the session.

The full frame at 100mm

Center sharpness is acceptable between f/8 and f/11, with some softness evident wide open at f/5.6. At f/16 sharpness is beginning to drop off a little due to diffraction. You need to stop down to f/11 to obtain acceptable edge sharpness.

Aperture	Centre Crop	Edge Crop
f/5.6
f/8
f/11
f/16
f/22
f/32
f/36