17-70mm lens (Pentax or Tamron advice please)

Started 4 months ago | Discussions thread
Hythloday Senior Member • Posts: 2,220
Re: Proof is in your pudding

Massao wrote:

Unfortunately, can't see those images.

The images were on Photobucket, but the reactions are clear enough.

How good/bad a lens performs is also depended on the camera. Below is a link to the Sigma 17-70mm in a Pentax K200D and a Pentax k3:

Sigma 17-70mm F2.8-4 DC MACRO HSM C Pentax on Pentax K200D vs Sigma 17-70mm F2.8-4 DC MACRO HSM C Pentax on Pentax K-3 (dxomark.com)

Generally speaking,  lenses perform better in newer cameras. My Pentax DA17-70mm scores better on my K-3. The sharpness in the centre and borders is better. My Pentax DA16-45mm also scores better on my K-3II, at least in the centre, but at the borders the sharpness is slightly better.

The Pentax DA17-70mm and the Sigma 17-70mm have one thing in common: the AF system is the weakest point. The Pentax DA17-70mm sometimes refuses to focus at 70mm, when contrast is low. Simply use quick shift and the problem is solved. But the Sigma 17-70mm is unreliable at focussing, as you will read in the link to my test.

 Hythloday's gear list:Hythloday's gear list
Pentax K-3 Pentax K-3 II Pentax KP Pentax smc DA 16-45mm F4 ED AL Pentax smc DA* 50-135mm F2.8 ED (IF) SDM +7 more
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