Originally posted by angerdan I have thought long and hard over which lens to get to pair with the featherweight Nikon 500PF, and which can give me the distance performance of the DA560. The Sigma 500f4S was high on my list because I already have the Nikon D500 and Z7. I know that conventional super telelenses will do better in ultimate IQ than the specialty lenses like the Nikon 500PF and Canon 400DOII, but the Canon and Nikon affair has taught me a thing or two, and true focal length can not easily be replaced with a TC when it comes to the ultimate lens test: distance rendering. TC's work great at close to medium distance, merely to get more pixels on your subject, but are a lousy proposition if more reach is what you want, unless you are already filling enough of the frame without TC and want the extra pixels. In general though: cropping the bare lens often beats using a TC when shooting distant subjects.
it is important to get close enough, reach out far enough, to let the camera do its work, AF wise, and have the neccessary subject isolation and distinction from the surroundings. This is especially true in daylight over longer distances.
So while I came close to going for the Sigma 500mmf4S or the Nikon 500mm f4E FL, I decided that I still will not be able to get DA560 performance over distance, simply because of losing the crucial 60mm of the bare lens.
I decided to save up longer and go for a 600mm f4 ór return to the DA560 when the new K aps-c body has top IQ.
The weakest point of the DA560 though, is its AF motor, which practically limits it to static shooting, and the pronounced color fringing which tends to add magenta and green stripes to water surfaces outside the plane of focus. But then again, the cause of that weakness: very few lens elements, is also the reason why the DA560 has immense clarity and is capable of very high detail without resorting to elaborate sharpening, and iso tends to stay low due to very high transmission for a f5. 6 lens.
A modern 600mm f4 lens will have all that the DA560 has, plus cutting edge AF and no color fringing, but my goodness, the prices for these lenses are sky high. The weight though of the Sony 600mm f4GM is identical to that of the DA560, so it is a tough choice. Nikon is set (rumored) to release its Z600mm f4 before the end of 2021, and having the Z7 already for all general shooting, would be somewhat more affordable.