Canon 2x Extender

[SubliminalThought]

Any of you guys have experience on using the Canon 2x Extender? Compared to other extenders like the Sigma and Kenko?

From my research, due to the Canon having sealing and flourite coated elements, its the better one to get.

 

[bwana]

I've got the 2x Kenko and IQ isnt an issue - light is - so I'm not sure if spending so much more is really worth it.