[Robert N]

Thank you all for your comments on my initial discussion between the SMC DA 18-55mm WR lens and the HD DA 16-85mm ED DC WR lens. The 18-55mm lens has given me some excellent results in the past (including high marks at my good level camera club). Looking at the LW/PH resolution comparisons from independent reviews, the lenses have comparable figures in the f:8/f:11 ranges, at around 30mm focal length. For landscape work, f:14/f:16 is often required for the necessary DOF (bearing in mind the diffraction effects after f:11). For use with the K-3 camera, what percentage increase in resolution do users feel they gain with the 16-85mm lens over the 18-55mm lens when using apertures in the f:8-f:16 range (I fully appreciate the 16-85mm lens has superior border and edge resolution at larger apertures). Bear in mind I shoot in RAW and sharpen as required.
Looking forward to your comments.

Read more at: HD DA 16-85mm F3.5-5.6 ED DC WR lens - PentaxForums.com

[Adam]

If you stop down past diffraction range you're going to degrade your image quality, F11 should be plenty for correctly-focused landscapes at a wide focal length.

[pentageek]

the lenses have comparable figures in the f:8/f:11 ranges, at around 30mm focal length

I think it is not very likely - I have 16-85, and used to have 18-135 (similar to 18-55 in terms of IQ), and I would not call image quality of these lens 'comparable'. But I digress - my point is that 'percentage' mentioned in your post is mostly irrelevant, because you can not see any difference between, say, 50% and 55%. I assume you are considering upgrade from kit lens to 16-85, and if this is the case, I think feedback from members of the forum was unequivocal - 16-85 is fine lens, definitely better than 18-55 or 18-135, with extra 2mm on wide end. If you are interested in 30mm range, maybe a prime is an option? DA 35/2.4 mentioned in original discussion seems to be a good candidate.