Quote Originally Posted by Joel Eade View Post
My experience is the same as with Kayaker ..... the loss of auto-focus will probably be a deal breaker for you but since it's a rental give it a try.....I am not very good at manual focus at high magnification.

The version III of the 2X converter can be used very successfully on f/4 or f/2.8 lenses.

With the 2X TC I can get very sharp RAW files from the following three lenses: 500mm f/4L, 300mm f/2.8L and the 70-200mm f/2.8L

I have seen plenty of very sharp images using it with the 400mm f/4L DO and the 600mm f/4L (I do not own either of these lenses)

If you need 800mm or more I would suggest you rent one of these to try out with the 2X TC

I suspect the 400mm f/2.8L would perform well too but I am mostly in to bird photography and it is not commonly used for birds.
Thanks for your reply. I don't have much experience with manual focus at all let alone at high magnification, so this will be fun to try. I have used the 2x converter on my 70-200mm f/2.8 IS L II and love the reach it gives me. I can get decent shots with that combo. 400mm is more than enough for the shooting I do. Looking forward to trying a moon shot at 800mm providing the night is clear. I'll probably shoot at 400mm while I have it, just want to try it with the 2x converter. I am going to be trying my hand at shooting birds, which I have never done before, so it should be an interesting week. Thanks for the feedback.