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

General Image Quality

Even before jumping in to our technical analysis of this lens, we can already say that for everyday shooting, the sharpness of this lens leaves nothing to be desired. Click on the image below for a full-resolution crop of a hand-held JPEG straight out of the camera. The image was shot at 85mm with a Pentax K-3, ISO 400, F8 and 1/250s.  Putting the lens on a tripod would make things even sharper!

Cropped sample photo - click for full size

Below is another hand-held 85mm shot taken at ISO 400, F8, 1/500s.  View the JPG file straight from the camera (K-3) below:

The Scene	Cropped - click for full size

We get a first glimpse of the nice bokeh this lens produces and the full resolution crop of the above illustrates how sharp this lens is:

Full resolution crop

We even managed to provoke moire in another hand-held parrot photo (look in the lower half).

Color and Contrast

The 16-85mm's color rendition is neutral to slightly warm, and the contrast is very good for a zoom lens. The unprocessed image shown below (developed from RAW without any adjustments) illustrates this:

Unedited RAW conversion

At short focal legths we observe plenty of contrast, almost as if a polarizing filter were used.  You can expect to get pleasing images straight out of camera when shooting with this lens, though at times post-processing enhancements can yield an even better result, as shown in the set below:

Metering and Exposure

Exposure is somewhat uneven across the aperture range. Wide-open the lens underexposes. Stopping down half a stop increases exposure to being correctly exposed. Exposure then drops back into underexposure again until F16, where exposure increases some.

The effect is illustrated in the series below. The images were shot in RAW (DNG) and not processed except for being downsampled to a width of 900 pixels. Click any thumbnail to enlarge and browse the images.

	DA 16-85mm at 35mm
F4.5
F5.6
F8
F11
F16

The unevenness is pronounced enough to stand out unless corrected in post-processing or via exposure compensation, and thus we find it quite disappointing that the aperture isn't calibrated better.

Flash Coverage

The photos bellow illustrate the on-board flash coverage with and without the supplied lens hood.  This test was performed with the Pentax K-3.

	Without Hood	With Hood
16mm
24mm
35mm
50mm
85mm

An external flash is desirable when shooting at 16mm.  At other focal lengths, the on-board flash offers sufficient coverage.

Stabilization

Pentax DSLRs feature sensor-shift Shake Reduction, and thus in-lens stabilization is not needed.  Shake Reduction can compensate for up to 3.5 stops of light, which enables you to hand-hold your camera at relatively slow shutter speeds without losing much sharpness (for stationary subjects).

Starbursts

With its rounded aperture and many lens elements this lens is not your go-to lens for shooting starbursts, as illustrated below, where we shot at 16 mm focal length. Our favorite for wide angle shots with starbursts remains the SMC (not HD) version of the Pentax-DA 15mm prime lens.

F3.5 (wide open)	F4
F4.5	F5.6
F8

While the rendering of starbursts is not geometric, the smooth rendering of point light sources at wider apertures can be appealing.

Tele Photography: DA 18-135mm Comparison

As suggested by one of our users we will in this section investigate the impact on the image quality at the long end if one replaces the DA 18-135 mm set to 135 mm with a cropped image from the 16-85 mm set at 85 mm.

We shot the scene with the 18-135mm at 135mm and with the 16-85mm at 85mm. In the latter case we cropped the image to get the same, narrow, field of view as the 135mm focal length provided. We present the results in three ways (click thumbnails to enlarge):

• Row 1: The scene (reduced resolution)
• Row 2: Full resolution crops (naturally, these have different dimensions)
• Row 3: DA 16-85: full resolution crop, DA 18-135: downsmapled to same size as DA 16-85 image
• Row 4: DA 18-135: full resolution crop, DA 16-85: upsampled to same size as DA 18-135 image

	DA 16-85 at 85mm	DA 18-135 at 135mm
1
2	Full resolution crop	Full resolution crop
3	Full resolution crop	Downsampled to match image to the left
4	Upsampled to match image to the right	Full resolution crop

The images were shot at ISO 100, F8, with the K-3 on a tripod. We examined the images at various F-stops and both lenses performed best at F8.

Note that the largest images are about 1060 x 1640 pixels. If your monitor cannot display the images at 100% when browsing in the lightbox you may want to download the images and check them out in your image viewer.

We can conclude that if you need the larger size and would have to upsample the image from the 16-85 to achieve that size, then you're better off shooting with the 18-135 (row 4). If you can do with the size of the image from the 16-85 then not much is gained by shooting with the 18-135mm and downsampling (row 3). The latter finding is a bit of a surprise, we would have thought that there were more to gain by downsampling.

The slider below better illustrates the difference in resolution between both lenses at their maximum focal lengths:

While we were at it, we also shot the 18-135mm at 85mm to see how it stacked up against the 16-85mm on even ground. Here are full resolution crops for comparison (click to enlarge and browse).

We would nominate the 18-135mm as the winner, but not by much.

Zoom Range

The general image quality is definitely approved throughout the zoom range. The range is well suited for a general walk-around and travel lens. The images were shot with our K-3 at ISO 100, F8.

16 mm	24 mm
35 mm	50 mm
85 mm

Finally, let's take a look at how much wider the field of view is at 16mm compared to 18mm. On paper 2mm doesn't look as much but at the wide end these two millimeters make quite a difference:

16mm vs 18mm field of view

Verdict

The DA 16-85mm zoom has a useful zoom range as a multi-purpose lens and the difference between the 18mm of a kit lens and the 16mm at the wide end does bear a practical significance for landscape and interior photography.  This is a handy lens for travel photography and can be used as a main zoom lens by beginners and advanced users alike.

Its general image quality (color & contrast) is very good, but the exposure accuracy is slightly uneven over the aperture range, something that you would only notice when shooting the same scene at various apertures. It is advisable to use the aperture priority (Av) or manual (M) exposure modes and keep the aperture fixed if this unevenness is a concern.  At times a slight exposure compensation may also be appropriate.