Sharpness at 135mm

For this review, the sharpness test is carried out by photographing a real-world sample, rather than a test chart. The Canon TS-E 135mm f/4L Macro Lens was mounted on a Canon EOS 6D Mark II, which was in-turn mounted on a sturdy tripod. Exposure delay was activated to prevent camera-shake. Any changes in tone you might see across the crops are due to natural light changes during the shooting session.

The full frame at 135mm

At the centre of the frame, sharpness is excellent even wide open (f/4.0). It remains excellent throughout f/5.6 to f/11, dropping ever so slightly (to still be very good) at f/16. Sharpness drops a little again at f/22, getting softer at f/32 and very soft at f/45. At the edges of the frame, the best sharpness occurs between f/16 and f/22.

Aperture	Centre Crop	Edge Crop
f/4
f/5.6
f/8
f/11
f/16
f/22
f/32
f/45