Compared with the EF-S 24mm pancake lens for APS-C format DSLRs, this full-frame compatible lens has the same diameter, but is more than twice as long and twice the weight. Still, it’s compact and manageable at 68x56mm and 280g. It has a more conventional build, based on 11 optical elements rather than just six used in the pancake. One aspherical element is included and Super Spectra coatings are applied.Another similarity is that the aperture is based on a 7-blade diaphragm, and the aperture rating of f/2.8 is the same.
One major difference is that this lens uses a ring-type ultrasonic AF system, rather than a stepping motor. Typical of the breed, it has a focus distance scale, along with DoF markings for f/11 and f/22. With a mechanically linked focus ring, manual focusing is available, without first the need to activate the camera’s focus/metering system. However, the rotational travel of the focus ring is quite small and less than ideal for manual focusing. Another major difference between this lens and the pancakes is that it features highly-effective 4-stop image stabilization.