Hi all, is the canon 300mm f4L telephoto lens compatable
with a canon 70d?
Also what's the views on a 18-135mm lens please?
18-135 is a massive improvement on the kit lens - all being well with half-decent light, you might even be able to have working AF on the 300mm F4 even with a 2x teleconverter (which would be 600mm F8) (but I can't promise anything above F6.3).
The 300mm f4 will only manual focus with the canon 2x TC on the 70D, you would need to look at one of the 3rd party TCs like kenko pro which might work, but you'll need to do a bit of research to find which one