Originally posted by pearsaab I also had an f 300 at one time...it was an excellent lens but was slower to focus than the da300...now that my da300 was really slow I was looking at the f300 again...it was super light...
This would be true on an older body, but the game has changed since the release of the K-5 II/IIs. Much of the information (even pf reviews) don't take into account the better AF of the K-5 II and K-3 we've had for only about 1 1/2 years now.
And if you were comparing on the K200D or something (rather than the K-5) forget it - of course the DA*300 will win in AF performance.
Plus keep in mind that the F*300 gives you audible feedback for every little final micro-adjustment, which could make it seem slower as well. But I think I subconsciously use the AF noise to help me click the shutter when it's in focus, even at a noisy event - so that may in fact help me.
In any case, aside from the perceived faster speed of the F*300, side-by-side I got more misses and more times the DA*300 completely lost focus. Now I mostly had the DA*300 on the K-5, and the F*300 on the K-5 IIs, so this could be some of the difference - but in theory this was the right way to do it, because the K-5's slower in-body AF motor isn't a factor with the DA*300's SDM bypassing it. The difference was significant enough that after a while I didn't even want to try the DA*300 any more, because I was missing too many shots. I was also borrowing a K-3 part of this time - I never got a good handle on how its AF compared to the K-5 IIs, but it certainly did well.