Originally posted by northcoastgreg Yes, the differences are insignificant. You wouldn't notice them in the gestalt of looking at an entire image. I'm wondering if these slight differences in resolution at long distances at the long end of the lens might be a consequence of Pentax's attempt to tweak the Tamron lens so that it renders better. Could it be that in an attempt to make the lens render in a more Pentax way a bit of resolution has been lost at longer distances? In my experience, my non-Pentax lenses do tend to be a little sharper at longer distances than my Pentax glass.
I was looking at some of the images over at ephotozine taken with this lens and they had one image of duck that was reasonably sharp, but featured a nicely rendered beak — very life-like and tactile. Maybe the Tamron wouild render that beak just as well, but without a comparison shot, how do we know? Pictures of distant cell towers and roofs and other trivial objects only provide a partial glimpse of what a lens can do. I want to see the kind of images I would use the lens for, were I to acquire it. Only then could I determine whether the lens is up to snuff.
I once downloaded files from Imagine Resources in a "discussion"with the famous Ian over the meaning of the 150 lw/ph between a 24 MP K-3, and a 24 MP D500. Even pixel peeping you had to believe there was a difference to see it. There as a little bit of teeny tiny barely noticeable fuzz that if you squinted really hard even pixel peeping looked little bit softer. To him it was a significant difference making it worth his while to buying a D500. To me it was barely visible if you were sitting in the right spot, looking directly at a particular part of the image and would have been easy to overlook if you weren't engaged in a stupid argument, oops I mean discussion. Pixel peeping a K-3 is the same as looking at a 60 inch print done at a real 109 dpi on my computer.
It made practically no difference even at 60 inches across. So it doesn't even have to be when looking at the entire image. Even pixel peeping it makes no practical difference. Unless you have specific part of the image that is too small to be resolved by 2700 lw/ph yet large enough to be resolved by 2850 /lw/ph, with in this case was some print black on white, and the odds of that happening are probably somewhere in the order of 5% (a lot less if you conser that not every part of photo must be razor sharp to be enjoyed) and the lack of detail was not noticeable on feathers, cloth swatches etc. anything but very fine printing. And IR were set studio shots they put every camera through. Your odds of producing two shots in real life that were in any way different would be remarkably low unless you used the worst lens you own. I have an FA 28-200 and an FAJ 18-35 that would be soft reproduced at 60 inch that reproduced at 36 inches would be absolutely as good as my best lens.
After about 2000 lw/ph, improvements in lw/ph are pretty much for bragging rights, 99.9% of the time. Case in point a Nikon D800 shooting buddy who was dead certain he was getting better images than me with my K-3. He was terribly disappointed, and pulled the famous, "my pictures are better but you have better PP skills than I do " excuse. I thought "If you don't have good PP skills why would you even pay for a D800 and shoot raw. Shoot jpeg man." But he was already hurting... why rub it in?
And he had enough money he could buy whatever he wanted.
Next time out his camera broke 4 days into a 7 day trip and he ended up shooting the rest of the trip with a point and shoot he borrowed from his daughter.
Shooting landscape and pixel peeping Tess and I can't tell the difference between her k-5 and my K-1, same shot, same lens (DFA 28-105) same tripod set up, adjusted for field of view. When I bought the K-1 I was set to tell the world about the huge difference 36 MP makes. Spurred on from years of promotion by jsherman and other D800 shooters. I ended up feeling a little foolish.... but I'm over it now.
I still love my K-1 and am happy to use it for the 2%-3% of the images where it might make a difference. Not a real world difference but a pixel peeping difference, if you can actually find that spot in the photo where it shows up because it won't be every where. Comparing Tess' K-5 and my K-1 I've never actually found such a place, but like other K-1 users, I have to believe it's there somewhere if I look long enough.