Originally posted by csa Norm, those are amazing for such this lens; very impressive!
People don't seem to realize with 13 elements in 9 groups and an 8.5 forum sharpness rating the 55-300 for example has an 8.55 rating and 12 elements in 8 groups. The 70-210 might be the best constructed most corrected consumer zoom, Pentax has ever made. If it wasn't for the fact that it's a film lenses and can ruin your images with purple fringing, I think it would be rated a lot higher. Based in part on price of course, it also has a 100% approval rating compared to 96% off the 55-300, and it's actually rated higher by forum users than the DA*16-50, a whole point higher than any kit lens. A little lower than the 18-135 but not much and higher than the 17-70. and much higher than the lens that share's it's current focal length, the 50-200. It's a lens that never gets the respect it deserves, and it has the added bonus of being one of the fastest focusing lenses on a K-3, albeit a noisy lens that can almost break your wrist when it locks focus.
The problem with it for me is it's a whole point worse than the 60-250, and it really is, regardless of how bad people might think the forum rating system is. But because of it's "focus breathing" it actually is better than the 60-250 for magnification at 15 feet or less. It has carved out a place in the Pentax universe other lenses like the 80-320 and various 70-210s and similar focal lengths haven't.