How does sigma dg 28-300 zoom lock work Tags: SLR Canon Zoom Cameras Last response: March 18, 2010 2:45 PM in Digital Camera Share lakeman February 1, 2010 6:11:55 PM Hello. I just got a Sigma DG 28-300mm lenses for my Canon Rebel XT. I am told that the lenses has a zoom lock. Where is it? How is it used? More about : sigma 300 zoom lock work Anonymous March 18, 2010 2:45:39 PM Sigma zoom lock, small toggle on base of lens that stops the zoom lens opening under gravity, it locks the Zoom at smallest mm setting or all the way in! m 0 l Can't find your answer ? Ask ! Publish Related resources zoom lock on sigma lenses...28-300. Forum SolvedHow does AMD's CPU socket locking mechanism work? Forum More resources Read discussions in other Digital Camera categories Camcorders Digital Photography DSLRs Point & Shoot SLR ZLR Kodak Nikon Sony !