I would like to protect the lens of my Nizo 561 Macro. i have been trying to find a lens cap for it, but I do not know what size I should I get. I read somewhere that it's a 52mm size. I ordered a screw on lens cap, but its way too big. Does anyone know what size I should get? I would like to get one that either screws onto the lens thread or goes over the lens. Thanks.