Originally posted by sculptor666 so two consumerish(?) ff zooms covering similar focal lengths(70-200, 50?-300) not sure i buy that. i'd buy a wide* prime or a wr hd 50mm macro though
The 70-200 f4 is going to be a better lens than the 50-300. I would think about it more like the DA *60-250 versus, say, the DA 55-300 PLM. The 55-300 is a nice, fast focusing lens that is quite compact and is a lot cheaper, but it isn't anywhere near the quality of the 60-250 either. The 70-200 f4 isn't listed as a star lens, but it is still going to be higher quality than the 50-300, it will be bigger and priced a lot higher -- say 550 for the 50-300 (this based on Nikon's price for their 70-300 variable aperture full frame zoom) and 1200 for the 70-200 f4.
There are plenty of pros who use 70-200 f4 rather than f2.8 lenses to keep the size down on their set ups and with high iso being what it is on the K-1 II, you could probably lose a stop on the aperture and still do pretty well -- assuming that the lens is sharp wide open.