Pentax F 35-70 f3.5-4.5

The Pentax F 35-70 zoom is surprisingly small for a zoom lens. It weighs only 235 grams and when completely retracted is less than two inches in length. It’s comparable in size to the Pentax K 50/1.2 or Pentax K 28/3.5. In other words, it’s about the size of one of Pentax’s larger normal or wide angle primes. It easily can be carried around in a pocket. When Pentax gets around to releasing their “limited” zoom, we can only hope that it will be around the size of the F 35-70.

How does the lens perform? It performs well, but nothing more. Its conspicuous merit is that it is consistent throughout its range. It’s as sharp, border to border at 35mm as it is at 50mm and 70mm. It’s a lens that won’t disappoint, although it also won’t stun or overwhelm. It does a number of things well, but nothing superlatively. It has decent but not outstanding resolution; it has decent but not outstanding color rendition; it has decent but not outstanding close-focusing abilities. Contrast is perhaps a weak point; but even here there’s really not much to complain about, as we shall see. Distortion is also a bit higher than one would expect in a zoom lens with such a limited range; but again it’s not a huge problem, and most zooms from its era are at least as bad in this regard.

Perhaps the only weakness the lens could be accused of is its rather narrow range and its cheap build quality. In all other respects this lens is a dependable performer; and given the bargain basement price it normally sells for on the used market (often under $50), there really isn’t anything to complain about. In terms of image quality, it falls somewhere between kit lenses such as the inglorious DA 18-55 II and the fine DA 16-45. Let’s take a closer look at what it’s capable of in practical application. No tests, just examples of what it does in “real” photography. All the photos are given mild, “common sense” post-processing, including sharpening (absolutely necessary, BTW, with the Pentax K-5).

Per usual with SLR lenses, the F 35-70 is sharper when stopped down to f8 or so. At 35mm and f9, it can deliver the following image:

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At 45mm and f8, it delivers comparable results:

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It keeps providing dependable results at 50mm, f8 as well:

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Nor does it disappoint at 70mm f7.1:

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The corners on APS-C DSLRs are quite good, as seen in this 100% crop:

Although the lens loses some resolution when used wide open, its performance is still respectable, as in this f4.5 shot taken at 70mm:

100% crop:

Bokeh is not a strong point with this lens, though it’s by no means bad or even below average. Given it’s focal length, it’s a bit of a slow lens and it’s difficult to create the requisite DOF to sufficiently blur out the background in an optimal manner:

The lens features a close-focusing ability. If you twist the zoom barrel past 70mm, it enters a “macro” mode. A useful feature, although it will not match what a dedicated macro lens can achieve. It only focus to a .25x magnification, as seen in this shot (taken wide open, a f4.5):

No, it can’t match what the DFA 100 f2.8 macro can achieve, but this more than adequate and handy when a macro lens is not at hand.

The Pentax F 35-70 is perhaps best fit as a modest upgrade from the DA 18-55 kit lens. While you lose quite a bit on the wide end (in terms of focal range), you gain better optics and further reach on the long end.

More examples: