For some time now I photograph with this converter. The image quality is good. I am happy. Currently, I use it mainly a Sigma 70-200mm f2.8 together with the OS APO. This results in the bottom line so a Endbrennweite of rich 400mm. The aperture loss to 5.6 I can currently cope well. Because of the money that is for me currently an unbeatable combination. Absolute buy recommendation for an affordable and yet very high quality telephoto focal lengths combination.