Pentax 16-45mm/4 Lens Review

by Josh Root; created August 2007

The Pentax SMC DA 16-45mm f/4.0 ED/AL is a fairly-compact wide zoom lens with a high image quality and a lower price than that of similar offerings from other manufacturers. This lens covers the wide to short-telephoto range and can do everything from capturing candid photos in a crowded room to creating nice portraits of a couple or small group. One of the most useful lenses that a photographer can have is a mid-range zoom.

The DA designation signifies that the lens is specifically designed for Pentax mount digital SLR bodies, which helps to keep the weight and size down. The ED designation signifies that the optical elements are made with "extra-low dispersion" glass, a more expensive and higher-quality material. The focal length of this lens makes it an excellent choice as an upgrade to the cheaper "kit" lens that is typically packaged with digital SLRs. The fact that this lens is not a 2.8 lens can be a limiting factor for the advanced photographer. However, due to the fact that this is a wide-angle lens, and it's only one stop slower than 2.8, most photographers will be able to compensate with a lower shutter speed or higher ISO level. Photographing indoors using available light is more of a challenge than with a 2.8 zoom or a 1.8 prime lens, though the 16-45 still performs well in these conditions.

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If you have a Pentax K10D, $650 (review), Pentax K100D, $520, or other Pentax mount DSLR, and need a wide to short-telephoto zoom, buy one right now from amazon.com and help to support photo.net.

Performance

As with all of the DA series lenses, the Pentax 16-45's image circle is sized to cover the APS-C sized CCD in Pentax DSLR cameras, cutting down on weight and size. The focal length range is 16-45mm, which is equivalent to 24.5-69mm in 35mm format. 24mm is about as wide of an angle of view as you can get without starting to get the distortion and optical effects that wide-angle lenses have. 70mm is a nice mid-telephoto portrait length, allowing you to avoid the unflattering effects of wide angle lenses when doing portrait photography.

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However, the f/4 aperture won't be helpful in creating a shallow depth of field for your portrait image. As this is a wide-angle lens, you would have a hard time doing that anyway. If you are looking for a portrait lens with the ability to create a very shallow depth of field, you might be better off with a fast prime like the Pentax DA 70mm f/2.4 Limited, $388 (review). The focal length of the Pentax 16-45 makes it a good choice for scenic or environmental portraiture. Due to the slower AF speed, capturing fast-moving action is somewhat challenging. Autofocus is slow when compared to the internal motor style of Canon's USM or Nikon's AFS. The Pentax is driven by the old Nikon-style "screwdriver blade" body motor. If you demand lens-motor driven AF for your Pentax DSLR in this focal length, you might consider the soon-to-be-released (as of Aug '07) Pentax DA* 16-50mm f/2.8 ED AL IF SDM, $634. If hyper-fast autofocus is not your main concern, the 16-45's AF will be satisfactory.

Optics

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The Pentax 16-45 is a complex lens design, with 13 elements in 10 groups including two aspherical lenses and ED elements (Extra-low Dispersion glass). There is noticeable barrel distortion at the wide end of the lens. This barrel distortion is not out of line for a lens of this focal length. Sharpness is quite good for a lens of this price and zoom range. Unsurprisingly, center sharpness is frequently better than corner sharpness on the wide end, but corner sharpness is surprisingly good as well. Most interesting is that, unlike many lenses in this focal range, the Pentax 16-45 does not lose much sharpness when used wide open.

Construction

When using the included petal-shaped lens hood, the smart design allows the 67mm filter and lens cap to be threads-free. The reverse-mounted hood allows access to the easy-to-grip zoom ring, but blocks the manual focus ring. As with all DA-series lenses, Pentax includes the Quick-Shift Focus System on the 16-45, which is similar to the Full-Time Manual Focus on some Canon lenses. Unfortunately, the Pentax 16-45's manual focus ring is not as nice as it could be. As it is, the ring is small, hard to find quickly without looking, rotates during AF, and seems to be added on as an afterthought. It also has the awful chintzy feel in use, typical of modern AF lenses irrespective of manufacturer. Of note, Pentax has remained dedicated to manual focus and actually includes the MF ring and distance markings on the 16-45. One unusual feature of this lens is that the lens extends when zoomed to the wide end of the focal range. That is to say, the lens is at its most compact size when set at 45mm. While not common, a few other popular lenses operate this way, most notably the Canon 24-70/2.8.

Weight is 12.9 oz (365g), which balances quite well with the Pentax K10D, $650 (review). The lens's dimensions are a fairly compact 2.8in x 3.6in (92 x 72 mm).

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Alternatives

Here are some other lens options to consider:

• Pentax DA* 16-50mm f/2.8 ED AL IF SDM, $634, Pentax's soon-to-be-released constant 2.8 internal-motor lens; said to be very well built.
• Sigma 15-30mm f/3.5-4.5 for Pentax and Samsung, $619, larger, heavier and more expensive than the Pentax 16-45. Faster and wider on the wide end of the zoom range, slower and wider on the long end.
• Pentax DA 18-55mm f/3.5-5.6 AL, $75, very cheap and light, the kit lens that Pentax includes with its DSLR kits. Better than many kit lenses, but not a stellar performer.

Conclusion

Overall, the Pentax SMC DA 16-45mm f/4.0 ED/AL is a very nice lens that could find it's way into any photographer's Pentax DSLR camera bag. It is priced so that a beginner would consider it as an upgrade to their "kit" lens. Yet it also has the image quality and well built construction that would give the more experienced photographer reasons to purchase it as well. When comparing its price to its image quality, the 16-45 is a very good value. Although the 16-45 does not have a 2.8 constant aperture, the constant f/4 aperture is only a single stop slower and many will consider the smaller size and significantly lower price more than worth the trade off.

Where to Buy

You can get this lens overnight from amazon.com.

Specifications

More

• Photo.net Pentax forum
• photo.net street photography tutorial
• Pentax web site

Examples

Josh Root

29mm, f/6.7, 1/500th, ISO 200. The wide end of the 16-45 gave me a large enough field of view to capture this juggler's performance while still staying at the front of the crowd.

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16mm, f/6.7, 1/250th, ISO 200. Another street performer photographed in motion. Again, the wide end of the Pentax 16-45 allowed me to capture the excitement of the moment and add some drama into the photo.

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45mm, f4, 1/90, ISO 400. While the wide end of the zoom has its uses, in this case I was pleased to have just enough zoom on the long end to isolate these two and bring the focal point to the mirror's reflection.

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50mm, f10, 1/250, ISO 200. While the AF is not blazingly fast, the lens did respond quickly enough to allow me to take some wedding images.

Josh Root

34mm, f/6.7, 1/180, ISO 100. The 16-45 on a Pentax K10D is a nice range for images of groups of people.

Josh Root

36mm, f/5.6, 1/180, ISO 400. Yes, that is exactly what you think it is, a stump with a bunch of old chainsaws stuck in it. What can I say, I love logging shows.

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16mm, f/5.6, 1/60, ISO 400. F/4 is a little slow for street photography, and I usually prefer something with a faster maximum aperture. In this case I didn't need it. Since there wasn't room to back up further, I could have used 1 or 2 mm's more on the wide end in order to get the woman's head in completely on the right.