After a quick tuning with the Sigma dock (I always adjust my lenses/TCs just in case), I took about 3000 pictures of a day lacrosse game. The focus speed is just a bit slower than with a Canon L lens. The quality is superb, almost as sharp as photos without the TC.

So this teleconverter is well built as we all have come to expect from sigma. I am using it on a sigma 150-600 contemporary (great lens). Unfortunately this lens is not super fast and not even a constant aperture. This is then made even worse when you put the teleconverter on.

As a rule, I have never found 2X tele extenders to meet my expectations with regard to resolution. I am happy to report that this one surprised me. I use it both on my Canon 6D and EOS 5M along with my Sigma 150-600 Contemporary.

I bought this to use with the Sigma 120-300mm F2.8 Sports DG APO OS HSM Lens for Canon. I already own the Canon teleconverters but found that they don't seem to perform reliably with this lens. I have been blown away by the quality of the images using the Sigma TC-2001... they are fantastic.

I used this with my Sigma 150-600 Sport lens to shoot the eclipse, and got great, sharp shots. Autofocus doesn't work with this teleconverter, which limits its usefulness. Extends my lens out to 1200mm, 1920mm on my 7DmkII

I bought both tc1401 and 2001. In a shop, I've tested on canon 6d sigma's converters and canon 2.x iii with sigma's 150-600 C and Tamron 70-200 2.8 VC. All 3 converters works on both lenses. But with Canon 2x on Sigma at 600, image is significantly worst vs Sigma 2001.

Much improved 2X converter. The lens is sharper, better color and contrast and better edge to edge than the older Sigma 2X

Used w. the 300-800 mm Sigma 5.6 I have to admit it has produced much better than expected. The days of a tele producing very poor results may be over! this has done very good work for me and even will autofocus most of the time on a Nikon 810.

I've tried a couple solutions to getting better reach with my DSLR over the past two decades. As time goes on it seems I throw more and more money and the desire to create deep compression and get background separation for a given subject - usually birds but sometimes elements within a landscape and...

Paired with the Sigma 100-600 lens it’s amazing! Better than expected! Sometimes it misses focus and hunts around but it’s nothing I can’t deal with. Photo posted below is shot with a Nikon d850 sigma 100-600 contemporary lens camera in DX format for extra reach paired with the 2x teleconverter.