HD Pentax-DA 16-85mm F3.5-5.6

Construction and Handling

The build quality of the HD Pentax-DA 16-85mm zoom is solid and confirms this lens as a premium alternative to the kit lens. The lens barrel is made of polycarbonate with two inner barrels that extend as you zoom toward 85mm. There is but the faintest wobbling even when the lens is fully extended.  Since this lens shares its physical design with the DA 18-135mm, it's possible that more play could develop over time (as with the other lens), but we did not observe any during our month-long testing.

The zoom ring is very wide, comfortable to hold, and allows for a secure grip thanks to the structured rubber surface. The zoom ring exhibits more friction than we usually see in zoom lenses. This prevents zoom creep, but we'd speculate that with use the friction will become less. The friction lessens in the long end when one zooms past approximately 75mm, probably caused by a change in the pattern of movement of the lens elements at the long end.

The focusing ring is placed between the camera body and the zoom ring. It is quite narrow and moves with just the right amount of friction. The focus mechanism has the Quick Shift feature which allows for manually fine tuning focus even in autofocus mode without having to flip the focus switch to manual. We do miss having a distance scale.

Lens Coating and Optical Construction

The lens elements are HD coated which according to Pentax enhances contrast and reduces light loss. The front element is SP (Super Protect) coated which should help repel smudges and dirt and also make cleaning the front element easier. We didn't abuse the lens and hence did not get to verify these claims; however, in our experience, the SP coating on all recent Pentax lenses has done an excellent job of making cleaning the front element easier

16-85mm Optical Design

The DA 16-85mm has internal focusing (IF). While the lens does extend as it is zoomed toward 85mm, focusing is accomplished by moving elements internally and thus does not impact the external length of the lens. The main benefit of IF is faster autofocus, so we're glad to see IF on this lens. Also, the front element does not rotate.

Optically, the lens is of the variable aperture type. At 16mm the lens has a F3.5 maximum aperture. This drops gradually as the lens is zoomed toward 85mm, where the maximum aperture will have narrowed to F5.6. This is a typical design for all but the most expensive zoom lenses and helps keep the size and weight in check. You do get a darker viewfinder at the long end and one cannot achieve as shallow a depth of field as with, say, an F2.8 lens.

The maximum available aperture changes with the focal length as shown in the diagram below, which also compares the 18-85mm to other lenses, including the faster Sigma 17-70mm "Contemporary":

In short, the maximum available aperture on the 16-85mm is similar to but not always the same as what you'll get with Pentax's other F3.5-5.6 standard zooms.

Filter Size and Lens Hood

The front lens element is quite large giving the inner lens barrel a characteristic flange at the front.

The filter diameter is 72 mm, an uncommon size for Pentax. A step-up ring to 77 mm can be used if you want to share filters with your larger lenses. In our judgment the lens hood is wide enough to be mounted even when a 77 mm step-up ring is attached.

The petal-shaped lens hood attaches via a bayonet mechanism.  In one out of the two copies of this lens that we tested, there was some play in the bayonet and the hood rattled slightly when we moved the lens around. This is not a problem for the image quality of course, but it did take a bit away from the otherwise solid impression of the build quality of this lens.

The lens hood has a detachable section on the underside. This is a traditional and most welcome feature on Pentax hoods and makes it convenient to adjust a polarizing filter while still having the lens hood affixed to the front of the lens. The detachable part even has the model number of the hood (PH-RBA72) engraved on it so that one easily can match the part to the appropriate hood.

The hood can be mounted reversed for transportation and storage. The cap is of the pinch type which means it can be attached and detached even with the hood mounted in the shooting position. All in all very user-friendly.

Physical Size and Weight

We were anxious to compare this new lens with our workhorse travel lens, the DA 18-135mm F3.5-5.6. Even though the two lenses have the same aperture range of F3.5-5.6, the extra 2 mm at the wide end (16mm versus 18mm) of the 16-85mm makes its barrel somewhat longer and wider than that of the 18-135mm. The new lens is also about  20% heavier.

Curiously enough, the 16-85mm lens also extends much more at the long end than the 18-135mm lens, even though its longest focal length of 85mm is much shorter. For good measure we also threw in the DA L 18-55mm F3.5-5.6 kit lens:

Pentax 16-85mm, 18-135mm, and 18-55mm (collapsed)

Pentax 16-85mm, 18-135mm, and 18-55mm (extended)

Our K-50 does look a bit overwhelmed by its new lens!

Dimension Comparison

The bottom line is that upgrading from a kit lens to the DA 16-85mm means trading compact size and low weight for image quality, but it is a worthwhile trade as you'll see on the following pages on image quality.

Lens Mount

On the rear of the lens we find a generous light baffle (1). The baffle reduces the risk that reflected stray light will impact the image (stray light hitting the sensor results in lower contrast and ghost images).

The DA 16-85mm sports a Pentax KAF3 lens mount made of metal. KAF3 implies that the lens has a built-in autofocus motor powered by the electrical contacts (2) and that there is no provision for screw-drive autofocus. In other words, this lens will not work with the earliest Pentax DSLR cameras (the *istD series and the K100/K110). We also find the usual stop down lever (3) and lens information contacts (4) on the mount. Technical details of the Pentax K-mount variants hereunder the KAF3 are explained in this article. Suffice it to say that this lens will work in all exposure modes and autofocus with all current and recent Pentax K-mount DSLR bodies.

Weather Sealing

The lens has several gaskets which protect its inner workings from dust and moisture. There is also a gasket on the lens mount as evident in the photo above. Using this lens with a weather-sealed camera (i.e. the K-50, K-5, K-3, K-S2, etc.) in rain or snow should pose no problem, but the combo is not waterproof and shouldn't be dunked in water or subjected to any environment with water under high pressure.

Verdict

The HD Pentax-DA 16-85mm zoom lens is very well made and shows appropriate consideration for image quality (lens hood included) and for the needs of the serious photographer (hood opening for adjusting a polarizer, excellent handling, silent autofocus). This zoom definitely belongs on the top shelf in the prosumer category and is a worthy replacement for the kit lens, and is perhaps also a lighter and slightly smaller alternative to the pro-grade SMC Pentax-DA* 16-50mm F2.8 zoom (albeit with a loss of up to one and a half stops of light).

We only have a couple of minor gripes regarding the physical aspects of this lens: It has no distance scale and the lens hood attachment can be a bit wobbly.

Additional Product Photos

Click on any thumbnail to enlarge.