Sigma 1.4 x Teleconvertor , any good with 150-500mm and Canon 60d?

[Big Rob]

As the thread title states I have found a reasonable (I think) priced Sigma EX APO 1.4x Teleconvertor,and was wondering if it will marry up well with a Sigma 150-500mm lens and Canon 60d.
I have read conflicting reports about it rendering the Auto-focus useless and increasing the focal length dramatically also. Has any one else used this combination or similar and found any problems. I mainly use my 150-500 for bird photography,and could have done with a bit of extra length for a couple of rarities that I saw over the weekend. I think i'm going to have to invest in a tripod and gimbal head also,so that might help with any issues this combination might bring up.
Thanks in advance,Rob.

 

[FlyingShrapnel]

I am not familiar with tele converters, but I think the 1.4x teleconverter will take up a stop of light, so at the long end of your sigma it will go from 6.3 (is it a 6.3 at the long end?) to 'beyond' 8 (5.6 to 8 is one stop) so yes, it will render af useless as most bodies stop auto focusing at f8 and I assume your 60d is the same

 

[andrewc]

According to Sigma website it will fit, but manual focus only and you may find the image degradation unacceptable.

Would you rather to crop a sharp image, or not crop a fuzzy image?

 

[artyman]

This was shot on a Canon 350D with the Sigma and 1.4 TC, as said manual focus but as DOF is so narrow it's usually pretty easy to see when you are in focus.