Originally posted by Pepe Guitarra The F*300/4.5 looks more like a real Pentax than the DA300/4. I kind of like the AF screw, it can be more reliable than the SDM, or other electronic. However, I am also contemplating buying a K3 and want to maximize the experience. I am on the fence!!
I choose the F*300/4.5 because I liked the IQ better.
But I wouldn't let the SDM scare you off. Most DA* primes like it never had a high incidence of SDM failures anyway. I decided against it simply for IQ reasons. I decided on IQ primarily based on images in the PPG
http://pentaxphotogallery.com/photos/gallery/query?camera=&lens=830, but I also got my hands on a DA*300 before I purchased the F*300 and my real life experience agreed with what I saw in the photos.
However, the DA*300 is still an excellent lens, and it has WR and is 1/3 stop faster.
The Advantages of the F*300 (besides my slight preference for the IQ - but "slight" can make the difference for me between
very good and
wow!) are that it's lighter, a bit smaller, and (the best I can tell) it focuses faster. The F*300 definitely focuses better (faster and tracks moving subjects better) on my K-5 IIs instead of my K-5. And the K-3 is supposed to be even better than that - the best Pentax DSLR you can get for screw-drive lenses.
The DA*300 is also fast-focusing enough for may action photographers, but I understand the SDM in it is only partially optimized for action.