Canon’s EF 40mm pancake lens is supersmall but you might feel its focal length is on the long side. On the other hand, the EF 35mm f/1.4L II USM is massive in size and cost. For full-frame DSLRs, this 35mm f/2 IS USM makes an ideal compromise. It’s an f-stop faster than the EF 24mm that’s well worth considering for APS-C format DSLRs, but isn’t much bigger or heavier, at 78x63mm and 335g, and both lenses are the same price.
The EF 24mm and 35mm lenses look very similar and both feature one aspherical element, Super Spectra coatings, ring-type ultrasonic AF, a distance scale with f/11 and f/22 DoF markings, plus a 4-stop image stabilizer. As well as being a stop faster, the 35mm lens has eight diaphragm blades that enable a better-rounded aperture when stopping down.