« on: April 02, 2012, 08:43:41 AM »
I had my 135mm f/2 L handy, so I put both TC's on it (F/8) and it had no problem autofocusing about 40 feet away, but it was quite slow.If this is with 1.4x + 2.0x, wouldn't this result in f/5.6? Can you also try with two 2.0x TC's?
Next, I taped the 70-200mm f/4 L IS and attached the 2X TC (F/8). I tried it at 70 and 200mm as well.So you mean unusable with 2.0x TC (and probably also with two 1.4x TC's).
My 70-200mm f/4 L IS was basically unusable with a 1.4X TC.