[Lak]

This test was done on a 300D on tripod, with manual setting. Shutterspeed was changed accordingly. This test did not harm any animals.
All done at 50mm. The 18-55mm was slightly off (at 49mm, yeah sorry my bad ).
Original pic with the prime lens at f-5.6



All these are at 100% crop focused on the "R" in "HERE"

Canon EF 50mm f/1.8 @ f-5.6 and @ f-8



Canon EF 28-135mm f/3.5-5.6 @ f-5.6 and @ f-8



Canon EF-S 18-55mm (300D kit lens) @ f- 5.6 and @ f-8



(adding in right, off-centre, bottom edge at f/5.6)

prime 50mm lens, 28-135mm lens, and 18-55mm kit lens


(adding in left, off-centre, bottom edge at f/8)