Compatability: Sigma 1.4x TC & 300mm f/4L

Im looking to get a 1.4x TC for my 300mm f/4L... I'd definetly like to save the $100 and get the Sigma instead. But I have heard abotu compatability problems with some Canon Prime zooms, of it not fitting on. Does anyone have any experience with the Sigma 1.4x TC and the Canon 300mm F/4L . Thanks!

I have the Kenko 1,4x Pro DG 300 & works like a charm.

The problem with some TC are not with PRIMES, just with some zoom lenses when the inner lens assambly can hit against the TC when it is moved/zoomed futher back.

So I asume that Sigma TC it´s also OK !!

Is it the IS version of the 300mm f/4 ? If not, I can try it when I get home from work...

I've used my Sigma 1.4x TC (non-DG) with my friend's 300 f4 L IS and it fits, AF works (though slower than the bare lens), and IQ is decent. I haven't tried it with the older 300 f4L non-IS, but I believe it would also work. Here's a link to a compatibility chart:
http://www.camerahacke​r.com …teleconverter/i​ndex.shtml

Romy

Oh, oops. I forgot to put that, yes, I have the IS version. Thanks alot guys, that answeres my problem; I am going to go order one now.