Lens review

Canon EF 28 mm f/1.8 USM

10. Autofocus

The focusing mechanism’s work, as it befits an USM device, is very silent. You hear just a very delicate swoosh of moving elements. The autofocus is also very quick. Attached to the EOS 1Ds MkIII, it needs just 0.6-0.7 of a second to run through the whole scale. What’s interesting, after changing the body into the 50D, the mechanism works even faster, because running through the scale takes just about 0.5 of a second.

Much less positive remarks can be written about the accuracy of the mechanism. In the case of the cooperation with an advanced autofocus system of the professional EOS 1Ds MkIII camera we observed as much as 12% of misses. Taking into account the fact that it happened in good studio conditions and the lens was on so advanced body, this result is hardly satisfactory. After putting the lens to the 50D the situation even worsened. The sharpness was set more or less correctly only if the initial distance scale’s position was near infinity. When the lens had to start from the position near the minimum focusing distance, the number of misses increased significantly.

Cooperating with the 1Ds Mark III the lens didn’t show any front or back focus tendency. On the 50D, for a change, we had a slight back-focus which was corrected without any problem by amending the settings in the appropriate tab from the camera’s menu.