ef 100 mm f2.8 IS L macro question ...

Fellows,

I own this beautifull lens and I know it can't be used with teleconverters ....

the question is : what if I use a 12mm extension tube between both ????

some people say it will work .... but I'd like to be sure before buying it ....

can anyone confirm this ????

many thanks !

PS: how about bellows in combination with this lens ????