bigma + tc = MF?

I have searched the net looking for information on this with no luck. I'm buying a 50-500mm Bigma, I have a D300, I already own the 1.4x Sigma APO TC but read that the Bigma will only work in Manual Focus with this TC. I then read that when using a Tamron TC 1.4x the autofocus works, although a bit slower and over 100mm only... however I am unsure if this works with my whole set-up. So.. my question is, D300 + Bigma HSM + Tamron 1.4x TC = AF??? For a fact? If so, I am going to sell my APO TC as its still in the box and buy the Tamron... and if its true, can someone provide a link for me to the Tamron TC, with MFG# so I make sure to get the right one.

THANKS

p.s. i know i need to learn to use mf but i would still like the choice of having af...

Dana, PM Harold Davis, he's got that lens and is very helpful. He'll tell you all about it :)
You can find him easily in Eager to Learn.

Hi Dana.

I have read in the past that it will not. The 50-500 is a F6.3 lens so with the 1.4X its an F13 lens so even if it did AF it would be very slow and in inaccurate, similar to a 500/4 with a 1.4X+2X.

Robert

Dana I would not try a converter with those lenses. If yo want to use a converter purchase a prime Canon or Nikon.

I really need the zoom, so a prime is out.. would love to have a nice 2.8 prime dedicated to birding.. but I guess I'll just sell the tele-converter on ebay, it won't fit any of my other lenses... Thanks! :)