So, to those of you that are running these, what do you think?

I only have a 70 - 200 F2.8 at the moment and can't justify buying a 100 - 400 or larger just yet.

Do these extenders work well, and are they compatible with all L series lenses/5D? I was planning to get the 2X extender from Digitalrev - 1.4X won't be large enough for what I need. It will turn the 70 - 200 F2.8 into a 140-400mm f5.6.

http://cgi.ebay.com.au/Canon-Tele-Ex...QQcmdZViewItem

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TD06 - Oink.

I run a 1.4x on 300mm 2.8 prime and it works very well, with the zoom you will probaly lose some auto focus speed, you will also lose some image quality with a 2x still should be fairly decent though, a 70-200 with 2x wont be as good as a 100-400mm but it will probaly be decent substitute, might wanna check out if you dont lose all auto focus some lenses you do as a saftey feature because the camera will hunt to much and can burn out the autofocus motor, but there are ways of getting around that putting tape over couple of the electronic tab things.