Terrific with a fast lens.

Using this with a Sigma 500 F4 and it is great. Optically I see zero degradation of image quality. Better than I expected in every way. Not sure how it will behave on a slower lens (i.e - 150-600 zoom) since autofocus will come into play with many camera bodies.

Great TC from Sigma

Great TC from Sigma.. Like other brands it does not work with ALL lenses, but I have used it successfully with Canon lenses as well as Sigma. Excellent resolution is maintained.

... of the sensor will reduce sharpness quality but would recommend the 1401

A much improved version from the apo version obviously what ever yo stick in front of the sensor will reduce sharpness quality but would recommend the 1401

Disappointing

This converter set the camera's AF micro adjustment to -20 but still showed serious back focus with the 7DII and Sigma 150-600mm Sport. Using the lens USB dock to add additional correction helped but back focus was still present. For me it was unusable for AF, returned for refund.

Lightweight; Strong Construction

Bad Back Focus; Blurry Focus; Slow Focus