Originally posted by snostorm For me, there are still a lot of ??? about this lens. IQ is probably the most important, but I'd also like to see how it plays with the Pentax 1.4x HD AW. Will it AF with reasonable performance at 630mm f8 with a K-3 in real life lighting conditions (anything dimmer than direct sunlight)? If so, and if the IQ is anything near what the published MTF seems to indicate, then I'll buy one, and also get the TC which I haven't required so far (I have all screw drive ultra teles at this time, so my Sigma and Tamron 1.4x TCs have been sufficient for my needs).
At 4.4 lbs, this would be considerably lighter than what I currently use to get past 500mm substantially, a 300/2.8 (6 lbs +) + stacked converters (2 stacked 1.4x TCs gets me 600mm f5.6 and a 1.4x stacked on a 1.7x AFA gives me 714mm f6.7). This lens, if it will AF reliably with the TC, will give me 630mm f8 and be about 2 lbs lighter (and should still be within my ability to hand hold effectively, plus it will give me some framing versatility, which becomes more important to me as my mobility becomes more limited with age.
To me, the cost is not daunting. I've lived in the world of premium ultra teles for quite some time, and expect to pay at this level for a lens that meets my specific needs. We'll just have to see if the D FA 150-450 falls into that category.
Scott
I like that you demanded a "reasonable" performance with the 1.4x tc at the long end. We must not get greedy with our demands, asking AF excellence from a 450mm f5.6 zoom when coupled with TC is a bit much. It's reassuring to know that the AF motors on these lenses are new and designed for speed. Right now we don't know much about them but I wouldn't be crazy to have our expectations meet on this front.
Moreover although the f6.7 might feel a bit slow, the new optics and coating should make it easier to bump up the ISO with these lenses, we might see a full stop improvement over older DA* or FA* glass. From the pictures we've seen so far at least the 150-450 + 1.4x IQ seems to be really excellent.