I have absolutely no experience with extension tubes. The way I understand it, they add magnification to a lens by making them longer? Anyway, I have an EF 100mm 2.8L Macro IS USM; love it, great quality, but... I want to get closer/larger with it... it's cool for an eye to fill up the picture--but it's a LOT cooler to have an iris filling the picture So, I found these Kenko extensions on Amazon... wondering, first of all, will they work with my EF lenses? And second, are these quality extensions? Does anyone have any examples of what they'll actually do with a macro?
Thanks, and I apologize if these are very stupid questions