[maryo]

Hi guys. Is anyone here using Pentax 17-70mm? Is it worth to buy over Pentax 16-45mm ? Thanks a lot.
Maryo

[Parallax]

I have one and I posted a review of it in the lens review section. In short, I like the lens very much.

[k100d]

DA17-70 side by side with Sigma 17-70: Pentax SLR Talk Forum: Digital Photography Review

[romancos]

DA 16-45mm and DA 17-70mm have both quite strong CA . DA 17-70mm reaches portrait focal length and would most likely be your all-time lense plus its SDM feature is real gift. If you can afford it, get DA 17-70mm instead of DA 16-45mm. Far as it goes with Sigma 17-70, it's softer at tele end, besides closer focusing distance for DA 17-70 is same 20cm as for Sigma, even though they don't have word "macro" in te lense name.

see Photodo review of the Sigma 17-70mm
Sigma 17-70mm f/2.8-4.5 Macro DC

Far as it goes with Sigma 17-70, it's softer at tele end, besides closer focusing distance for DA 17-70 is same 20cm as for Sigma, even though they don't have word "macro" in te lense name.

see Photodo review of the Sigma 17-70mm
Sigma 17-70mm f/2.8-4.5 Macro DC

I just wanted to interject and say that sometimes a little softness is good for portraiture.
Especially for older peoples skin (and girls over 20).

[frank]

DA 16-45mm and DA 17-70mm have both quite strong CA . DA 17-70mm reaches portrait focal length and would most likely be your all-time lense plus its SDM feature is real gift. If you can afford it, get DA 17-70mm instead of DA 16-45mm. Far as it goes with Sigma 17-70, it's softer at tele end, besides closer focusing distance for DA 17-70 is same 20cm as for Sigma, even though they don't have word "macro" in te lense name.

see Photodo review of the Sigma 17-70mm
Sigma 17-70mm f/2.8-4.5 Macro DC

Actually DA1770 can only focus as close as 28cm w/ a mag ratio of 0.31x (the Sigma is 0.43x when focused at 20cm)

From my own experience, the Sigma 1770 is pretty nice at tele end, better than it is on the wide end, probably due to slightly focusing error on the wide end on both my K10D and K20D. I myself have done a quick comparison between these two lenses, the Sigma 1770 is sharper w/ less CA in almost entire focal range. Probably the DA1770 I tested had some focusing problem? And also, seems 17mm on the Sigma is slightly wider than the wide end of DA1770.

Pentax DA17-70/4 vs Sigma DC 17-70/2.8-4.5

[TourDeForce]

DA17-70 side by side with Sigma 17-70: Pentax SLR Talk Forum: Digital Photography Review

I just wanted to interject and say that sometimes a little softness is good for portraiture.
Especially for older peoples skin (and girls over 20).

Excellent point, however the Sigma does have that Sigma yellow cast signature. It is minimal on this lens, but it is there. Easily correctable in post processing, but I HATE to post process. I'm a purist, I guess.

The review linked above also suggested the Pentax has slightly less distortion at the wide end, but if you look at the pictures, the left edge of the overlay frame clearly shows the Sigma has less barrel distortion.

Either lens would be a great walk around bit of glass. Not terribly expensive, fairly good performance. I like the Pentax colors better, but the SDM doesn't allow auto focus on K100 so it was Sigma for me.

If you're gonna do portraiture, get an A series 50mm 1.7, manual focus all the way, and call it a day.