daletu wrote in post #2726459
I am thinking about getting a 1.4x converter for my Canon EF 100-400mm F4.5-5.6L.
It's going to be either Canon 1.4x or Kenko 1.4x Pro 300.
But I have some questions before I decide which one I want to get.
I know AF will not work on both converters unless I use the tape trick.
And I also heard using tape trick on Canon 1.4x converter will have risk of destroying the AF motor.
I don't understand why?
What about Kenko 1.4x?
Will tape trick on Kenko 1.4x have risk too?
Both TC's will act the same way. The Kenko is good, but a bit soft on the edges. The Canon is much sharper all around.
As you look at the end of the TC which attaches to the lens, you will see a row of of 11 pins. These are electrical contacts to transmit info from the lens and the camera. Tape off the 3 left-most pins. I use a small bit of gaffers tape, but any non-residue tape will work.
This will fake the camera into not "seeing" the TC and you will have AF....somewhat slowed, particularly in low light, but it will still work. The 100-400 seems OK with the 1.4x...with 2x it hunts too much.
Actually I do not tape the pins on the TC. On the 100-400 I tape the pins on the lens (mirror image to the TC pins). This way the TC works on the 100-400 "faking" the camera to think it is still max. f/5.6 at 400mm, but will properly report it's (TCs) presence when used with the 70-200 f/2.8.
The "hunting" is what could damage the AF motor...if the person doing it was silly enough to keep trying to use the lens that way...i.e. continually failing to AF properly and "hunting" from end to end.