YONGNUO extension EF 2x III Lens Electronically controlled for Canon EOS EF LF470 (Electronics)
I had bought this extender to get with my EF 200L II 2.8 to 400mm. Unfortunately, the focus was very poor over the entire image field. The image at 400mm F / 5.6 did not show more details, rather less than a corresponding portion of the image without
