I own a first generation Canon EF 2x. I decided to skip the EF 2x II because there were no optical improvements in it. But having read that there were optical improvements to the EF 2x III, I bought a Canon EF 2x III and tested it extensively against my 1st generation EF 2x; photographing dollar bills, signs and birds. Sigma 150-600 Contemporary and Canon 2x Mk III Extender (APS-C) I recently got a hold of the Canon 2x Extender Version III. I primarily got it to pair with a Canon 70-200 f2.8 MkII to take it up to 400 mm, but I was interested in seeing how it worked with the Sigma. The following 2 images were taken on a tripod, about 50 yards out from an Canon EOS 7D Mark II Canon EF 500mm f/4.0L IS II USM Sigma 150-600mm F5-6.3 | C Canon EF 100-400mm F4.5-5.6L IS II Reply Reply with quote Reply to thread Complain Canon EOS R5 Sigma 50mm F1.4 DG HSM 85mm F1.8 USM Canon EF 135mm F2L USM Canon Extender EF 2x III +16 more 150% for the TC vs 300% without, so neither get I am also considering getting the new Tamron 150-600 lens, pending reviews. I was just curious if a Canon extender, specifically the canon EF 2X III, will work on the Tamron and/or Sigma lenses. Note that I currently own the Sigma 1.4x teleconverter but I'm not very happy with its IQ. sigma. Sigma 150 - 600 mm Sport lens for a Canon 7DII Cam - Page 2 - Canon Community. 08/18/2023: Canon EOS R5 C training series is released. 07/31/2023: New firmware updates are available. 05/31/2023: New firmware updates are available. 05/18/2023: New firmware updates are available. 03/30/2023: New firmware updates are available. Because I still own the 1.4 III and 2X III extenders, I'm actually trying to sell my Tamron right now in order to get the Canon 100-400 II, as it is sharper. With the 1.4 extender, it's 560mm, and apparently the Tamrons & Sigmas are actually at about that reach anyway, not a true 600mm. \$\begingroup\$ @Matthew I've never directly compared the EF 70-200mm f/2.8 L IS II + EF 2X III to the Tamron/Sigma 150-600mm lenses because I don't have much use for a telephoto lens that slow. Most of the sports/action I shoot is indoors or outside under the lights at night. ni8E7F.