Canon Community

I have a Canon 5d mii camera and had purchased a Canon EF lens : 75-300mm : 4-5.6 IS USM many years ago for a Canon t90 and would like to get an extender (tc) for the DSLR and lens. I have looked at the compatibility charts for the Canon 2x and 1.4 t...

I have a 5d Mark ll and am interested in an extender (doubler for us old folks) and is it true thatthere are compatability issues? There are only certain brands and / or  models that I can use w/ this camera?