Teleconverter question

[Erikerodri]

Hi everybody I currently own the sigma 70-200 2.8 os lens and I love it on my 6d. I have recently taken it to mma fights that I have been shooting and have run into kind of an issue. I need a bit of an extra reach at about the 280-300mm range. Shoul I buy a teleconverter? I have very little knowledge on teleconverters so I a hoping you guys can help me out with specific models. The camera settings tend to differ venue to venue but I try to keep my camera around f4-5.6 for the majority of fights (occasionally 2.8 when i am focusing on one person like a winner or something) 1/500 and adjust the ISo from there. I've been getting decent shots but I've been having to crop quite a bit. Any suggestions for me would be great!

 

[Maxaperture]

A couple of months ago, I would have said go for the new mkIII TC from Canon, but, I have the 2x MkIII and it doesn't work with my Sigma 150mm 2.8 OS Macro.

It's a boring answer, but hire and try before you buy.

 

[rs]

[quote author="The Digital Picture"]
This lens is also compatible with the Sigma 1.4x EX DG APO Teleconverter and the Sigma 2x EX DG APO Teleconverter. The teleconverters will make a more significant difference in magnification at the lens' native MFD.[/quote]
I'd personally go for the 1.4x TC myself if 280-300mm is what's required. You'll get 280mm with the TC, and cropping that small amount is better than the results you'll get with a 2x TC fitted. You'll also get f4 as an option with the 1.4x TC, whereas f5.6 is wide open when using the 2x. Here are both combos, both at f5.6:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=806&Camera=453&Sample=0&FLI=5&API=3&LensComp=806&CameraComp=453&SampleComp=0&FLIComp=6&APIComp=2