Originally posted by brntoki How do Pentax lenses really stack up, optically speaking, to Canon, Nikon, and even Tamron and like third party makers?
i give my 2 cents here :
look at the end of my post to see what gear i got. i use quite often the Canon 40D and 70-200/2.8 I, 50/1.4 and the 17-85 kit lens of a very good friend. used from time to time Nikon D700.
about the kit lens : Yes, kit lens are not the best top notch lens. However, to be honest the 17-85 is probably the worst kit lens i've ever own, and that day i realize that the 18-55, even if not the best lens, is very good. stop it a bit and it's quite sharp, a real pleasure to shot with it.
The Canon 50/1.4 and the DA*55 are quite on part about sharpness and pixel peeping (for me). The Canon focus faster, but not always better.
The main "problem" for me is that the Canon have a very hexagonal aperture wich create a distracting bokeh.
For the construction, i prefer the DA*, even if the Canon is not bad at all.
i never used any Pentax competitor of the Canon 70-200, so i can't tell. The Canon is very good, and has a very "WOW" factor. But it's heavy like a tank
Overall the competitor lens are very good, but unless you DSLR or the lens is badly calibrated, on a 20" inch screen (20x30 cm approx), you don't really see any notable difference. However i prefer Pentax lens, which tend to be more metal than plastic/resin than competitor, and more compact. I do a lot of rockclimbing and i bring gear on cliff, so i need to be light even if i take a lot of gear.
For me, as said before, just ask yourself what do you need to do the job, and which brand offer it at the best price for you, for the best quality possible. So if you never gonna do birding, don't say "Canon or Nikon, because they have more extrem telephoto (that i will never use)".