Excerpt: Received this as a gift. I am basically using it with my Sigma 120-400mm Telephoto Lens to shoot wildlife. I was well aware, when I started using it that there would be a loss of F Stops and no Auto Focus. I am fortunate to use this teleconverter with my Canon 6D as the pictures are awesome when shooting with high ISO settings. So far I have been blown away with the quality of this teleconverter. My pictures are sharp and well exposed.
Excerpt: I'm using this converter on the Sigma 150 to 500 mm lens. It works well on this lens. I haven't been able to try the converter on any other lens. Compatibility and that why I only gave this converter 4 stars out of 5. From what I have found so far is it works well on the 150 to 500 mm lens. autofocus does not work and it what I have expected from the compatibility chart.
Summary: Effectively doubles the focal length of my Sigma 70-200 2.8 APO DG HSM for my Nikon D610 which is a full frame camera. So, for $300 I have a zoom lens that goes from 140mm to 400mm at a reasonable aperture of 5.6 for the entire zoom range. I do not use this professionally and I am very happy with the quality of the image although it does lose a little contrast with the extender which is easily adjusted in post processing.