Comments on new review of 600mm II just posted

[HDNitehawk]

But really the deal breaker for me would be AF performance with extenders. If it's like the older extenders were AF is reduced by 50% with the 1.4x and 100% with the 2x that would push me over the edge for the 800mm.

Unless you have a 1 series body you will not be able to focus either of those lenses in Auto, unless you tape the sensors.

The OP mentioned he used a crop body, for a crop body I am more impressed with the 600mm with the 2x ISO charts than the 800mm with the 1.4x. The reason is that the crop body will not even be using the corners. The mid frame of the 600mm than the 800mm mid frame, and the 800mm in the center has a very slight edge. The 800mm wins in the corners, but unless you are full frame the corners do not matter. In actual use I don't think you will notice much difference between these two combinations unless you are full frame.http://www.the-digital-picture.com/R...mp=3&APIComp=1

Really I am not that impressed on any of the lengths ISO charts longer than the 500mm with the 2x, I think at 1200 and 1120 the 600mm and 800mm are loosing to much. http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=745&Camera=453&Sample=0&FLI=2&API= 0&LensComp=459&CameraComp=453&SampleComp=0&FLIComp =3&APIComp=1

Edit; One other point, I don't think the 800mm ISO is really beating the 600mm with the 1.4x;http://www.the-digital-picture.com/R...mp=1&APIComp=1