So I have just bought a new Canon camera and figured my Sigma 24mm 2.8 Superwide lens would be compatible with it, as it is an EF mount. The lens itself was given to me second hand and I had just been using it on M4/3rd cameras, so never needed to take of the adapter. Im trying to now but it won't even budge at all, Am I just being an idiot and its all part of the lens? Also this 'adapter' also acts as aperture, as it has a turning wheel to help adjust. I have attached pictures to see if anyone can help/give any advice!?
P.s There is a small hole where possibly the adapter release button may have been?