Will this TC it ever receive firware upgradeto accept Sigma's 100-400? As Sony has limited Sigma's ability to use the Sony e mount for lenses only, and not for TCs also, Sony should make the TC able to accept sigma lenses as well. "As you noticed, yes, we released a new TELE CONVERTER TC-1411/2011 for L-mount camera, but not for Sony E-mount camera, which must be unreasonable for you. As you may already know, we are licensed from Sony to design and produce Sony E-mount lenses, and it must be done in accordance with Sony E-mount specifications and license agreement. In the specifications and agreement, there are no statements on teleconverters. So, this is why we cannot design and produce Sony-E mount teleconverters. So, at this point, we have no concrete plan and schedule for making TELE CONVERTER TC-1411 in Sony E-mount. We are so sorry we are letting you down. If you have any questions, please do not hesitate to contact us. Again, thank you very much for being our customer. Have a great weekend!Best regards, SIGMA CORPORATION Customer Support Department "... Read More  Hide

I have the 1.4x teleconverter on my Sony 200-600mm mounted on an A6400. A lot of my photos are longer range birds. I had read mixed reviews about pictures getting soft on the upper end. In good light, you'd need to pixel peep on a well composed photo. For closer shots, I could not pick out a photo taken with the 1.4 compared to not using one.... Read More  Hide

Excellent quality when extra “reach” is needed. No noticeable quality lost but minimum aperture on 600mm is f/ 9.

The Sony 1.4 tele converter is just what I need to capture amazing closeups using my 100-400 G Master tele. It focuses fast as well.