Wow its almost like I post a thread with questions or problems every other day. Sorry, but I just got my sigma 105mm macro lens, and was extremely impressed, in the box I got a extension hood and screwed it on gently. Im extremely good with my stuff so when I say gently, it was extremely gentle. And took lots of shots, went to take it off and wont come off, I tried hard enough to where my vains were popping out of my hand almost. Which is FOR SURE not good for the lens so I am not going to try again because it just might break. Help please?