[superdave]

I'm afraid you won't find much to make you happy between these. The FA31 is a bit sharper than the 35 Limited in the corners, and stopped down, that is probably the best that is possible in middle focal lengths. The only other option is to shoot panoramas and crop so the entire frame of the image was taken from the center of the lens.

Here are the 31 and the 16-85 side-by-side, at f8, on a tripod. The 31 is better, not by an earth shattering amount.




I think the 31 ended up focused slightly further away, since the close bush and handrail on the right is a bit blurry; I think that's entirely because of bokeh, my lens isn't decentered. The distant objects on the 16-85's edges are slightly burry, so again, I think it's not focused quite at infinity. If you really want corner sharpness, there is some element of technique that comes into play as well.


EDIT: I have also posted the other photos I shot around the same focal length, the Sigma 17-70 (first version), the Sigma 30/1.4, The 18-135, the 16-50, and the old, venerable 18-55. Feel free to download full res copies and take a look if any of this makes a difference in your decision process.

What I really learned is I need to be more precise in focusing when doing these comparisons. The 18-55 and 18-135 are the only ones with moderately weak-ish borders. The 30/1.4 has abysmal borders for a fast prime, the others are at least in the same league.

Wow, thank you for the samples!

I looked at them carrefully and I think I may give a new try to the 16-85mm. I rank it 2nd on your samples, with 31Ltd 1st but it is too expensive for me. The left side of the image look a little softer than the right side, but by a hair.

After a fresh look at my own samples, I think that my copy was a little misaligned with the right side softer than normal on the wide end, and the left side softer on the long end. I was a little disapointed by edge quality when I tested the lens, but after having tested more lenses which weren't better, I think that my judgment was altered by the sigma 18-35 that I tested just before, and 16-85mm is above the average. I still not like the edge quality at 16mm, but now that I own the 11-18, I can live with that. At 24mm f/8 edge are better than my old 12-24mm, so not bad finally. At 35mm it look worse than at 24mm, but maybe because of a misalignment. At 50 and 70, the lens is not as good as my 50/1.8 and 70Ltd however...

---------- Post added 16-05-19 at 11:44 ----------

Not earth-shattering? I'd say it's a pretty dramatic difference in detail, colour rendition and contrast. Without looking too closely, I'd say the 16-85 image is the worst from the five Pentax lenses, and on par with the two Sigmas.

I won't say that, or may be you didn't looked at the good image.
18-135 is the crapiest, sigma 30 is a joke for a prime, 18-55 is a kit lens, 16-50 is not as good as 16-85 (on the right side, but as good on the left side), 31 Ltd is very good!

Thanks for sharing samples, however I cannot see the quality on resized image.

[mikesbike]

I'm not sure which is which lens, but the 2nd photo of those here by Kozlok shows much more detail and contrast than the first one.

[Kozlok]

Thanks for sharing samples, however I cannot see the quality on resized image.

You can dowload the full sized samples from my flickr and use the lightroom compare feature.

Not earth-shattering? I'd say it's a pretty dramatic difference in detail, colour rendition and contrast. Without looking too closely, I'd say the 16-85 image is the worst from the five Pentax lenses, and on par with the two Sigmas.

I think you may have them in the wrong order? Check the file names 0303 is the Sigma 17-70, 0291 is the Sigma 30, 0238 is the 18-135, 0219 is the 16-50, 0197 is the 18-55, 0281 is the FA31, and 0170 is the 16-85.

[Sandy Hancock]

I was going by the lens ID in the flickr EXIF

Anyway, the FA31 was the best - by a comfortable margin. As it should be.

[RGlasel]

the FA31 was the best - by a comfortable margin.

I agree with you on the FA 31, even after downloading full-resolution images. The DA 18-135 is much worse with the railings in the foreground, but if I zoom in on the radio and hydro towers 1/3 in from the left edge, I would say the 16-85 is the worst for both the towers and the trees along the ridge, and the 16-85 certainly doesn't excel in colour contrast. To my eyes, anyway..