I found some videos showing the AF performance of the new Kipon EOS-M43 AF adapter, and I'm quite surprised at how good it is. This is particularly interesting for telephoto users, because it greatly increases the number of fast telephoto options available to us. The three lenses I'm really thinking of are the 70-200 f/4 L, 200 f/2.8 L, and 300 f/4 L IS. If you do a comparison of size and price between the 70-200 f/4 L and 40-150 f/2.8 + 1.4x, we get the following: $285 (Kipon Adapter) + $650 (Canon 70-200 f/4 L) = $935 $350 (Olympus 1.4x) + $1500 (Olympus 40-150 f/2.8 PRO) = $1850 Granted, the Olympus combo gives you a bit more on either end (56mm vs. 70mm on the wide end, and 210mm vs. 200mm on the long end). But at a difference of more than $900, I don't think it's worth it. If we take the above combo, and look at weight, we get the following: ???g (Kipon Adapter) + 705g (Canon 70-200 f/4 L) = ???g 170g (Olympus 1.4x) + 880g (Olympus 40-150 PRO) = 1050g While we don't know what the Kipon Adapter will cost, you would think it would have to weigh less than the Oly 1.4x TC, since it contains no glass. The lens weight difference is 175g, plus the weight difference from the adapter, and you've got to be close to a 250g difference. So while the Canon combo will likely be a couple of inches longer, it'll be $900 cheaper (even more if you pick up the Canon lens used) and likely 200-250g lighter, all while delivering what appears to be acceptable AF performance. I'll definitely be keeping my eye on this, as it could give m43 users a gateway to some nice fast telephoto options that currently don't have in native lenses.