Pentax 17-70mm Lens Comparison

Conclusion and Ratings

After comparing three lenses as similar as our test subjects, the obvious question is: which one is the best choice? The answer is not simple and the best choice will probably be different for different users.

All three lenses offer good build quality and ergonomics, great optical performance and versatile packages. The Sigma v1 is smaller, is better at close focusing, is faster at 17mm and its traditional screwdrive AF is more reliable. It might have a slight edge on image quality over the Pentax. The Pentax has faster and nearly silent AF, some weather sealing, is faster at 70 mm and offers quick-shift MF. The Sigma v2 also has silent and fast AF, is faster over the whole range and includes built-in SR, but is much heavier and is not as good as the v1 regarding close focusing, in addition to being a battery hog. Its image quality is about as good as that of the other lenses, a tad worse than the Sigma v1 if we're splitting hairs.

Because of the Pentax lens’s hunting problems, we feel the Sigma lenses are a better choice. It must be stressed that we have tested only one sample of the Pentax lens, and it is possible that we have been given an imperfect lens. Nonetheless, we feel the Sigmas' more varied perks still make them better “walk-around” lenses, capable of facing a larger range of shooting situations. The v1 is only available used nowadays, but constitutes an interesting package, given its smaller size and better close focusing. The v2 isn't much of an improvement regarding optical qualities, but packs features not found on the other lenses tested here.

Pricing and Availability

The Sigma 17-70mm F2.8-4.5 (v1) was discontinued shortly after the debut of its successor. Our lens database currently indicates a second-hand price of just $350.  The Pentax 17-70mm F4 retails for $549 in the US, while the Sigma 17-70mm F2.8-4 (v2) retails for $469.  As the Sigma 17-70mm v2 is more readily available than the v1 and cheaper than the Pentax, and more feature-packed than its predecessor, we feel it deserves the best value rating of the bunch.

Pros and Cons

Sigma 17-70mm v1

Sigma 17-70mm v2

Pentax 17-70mm F4

Most compact size

Highest Magnification

Reliable AF

Slightly better IQ

Noisy & Slower AF

Slower aperture at 70mm

Silent & Reliable AF

Fastest AF

Fastest aperture overall

Excellent value

Heavy


Silent AF

Quick-shift manual focusing

Constant aperture

Internal focusing

Tendency to hunt even in good light

Expensive


Ratings

Sigma 17-70mm F2.8-4.5 (v1)

Sharpness 
 9
Aberrations 
 8
Bokeh 
 8
Autofocus 
 7
Handling 
 9
Value 
 9
Features 
 7
Overall 
 8.1 (Very Good)

Sigma 17-70mm F2.8-4 (v2)

Sharpness 
 9
Aberrations 
 8
Bokeh 
 8
Autofocus 
 8
Handling 
 8
Value 
 9
Features 
 9
Overall 
 8.4 (Very Good)

Pentax 17-70mm F4

Sharpness 
 9
Aberrations 
 8
Bokeh 
 8
Autofocus 
 7
Handling 
 9
Value 
 7
Features 
 8
Overall 
 8.0 (Very Good)

All in all, the three lenses come very close.  We tended to favor the two Sigma lenses slightly over the Pentax, though each lens has its own merits and hiccups as noticed in the pros & cons section.

If you currently own any of these lenses, or decide to pick one up, we invite you to share your thoughts in our Sigma lens review database or Pentax lens review database!

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