Comments about Sigma Sigma 2x EX DG APO Tele-Converter AF for Canon EOS Cameras:

I recently purchased this teleconverter along with SIGMA'S 70-200 f2.8 OS lens and am very pleased with the added reach. Buy using them together, I have the flexibility of doubling my focal range to 140-400mm while maintaining a f-stop of 5.6 and the tack sharpness and consistent focus I am accustomed to. It's nice to have flexibility without carrying a second lens for those distant shots! (Please select this teleconverter carefully, as it does not work with all SIGMA lenses).

Comments about Sigma Sigma 2x EX DG APO Tele-Converter AF for Canon EOS Cameras:

I am please with the functionality of this product. It would be nice if it would allow for Auto Focusing but that is not a show stopper in my opinion

Comments about Sigma Sigma 2x EX DG APO Tele-Converter AF for Canon EOS Cameras:

I bought this product because there are times when my 200mm lens just isn't enough but I couldn't afford a bigger lens at this time. I knew that my f/2.8 would become an f/5.6 and I would lose some speed but that is okay because I will only be using the converter in the daylight.
Overall I had a good experience the first time I used it. I shot a motorsports event and the only downfall was sluggish focusing. It performed well if the focus stayed about the same, but when the camera loses its focus it takes a long time to come back in. I was happy with the images I got with it and it lived up to my expectations.