I currently own a Canon 70-200mm f2.8L USm IS II lens. I also own 2 Lens extenders..1.4X and 2.0x. Is it safe for me to stack these extenders on to the Canon lens? Canon 70-200mm + 1.4x +2.0x? I also own Canon 24-105mm F4L, Canon 24-105 f2.8L and canon 100mm f2.8L lens - can I use canon extenders on these lenses? Thank you for your advice.