If the Pentax HD D FA Macro 100mm F2.8 ED AW ($549.95) looks a lot like the older D FA Macro 100mm F2.8 ED WR (introduced in 2009), there's a good reason. Instead of developing an all-new design, Pentax went back and updated some optical elements inside the old lens to improve picture quality on high-pixel digital sensors. The lens succeeds on that front, delivering great-looking close-up photos, but its screw-driven telescoping focus system feels like something from the previous century. You'll have to look to other camera systems for a macro lens with a more modern bent, however, as this is what you get with Pentax.

Compact, Sturdy, and Sealed

As far as macro lenses go, the HD D FA Macro 100mm F2.8 ED AW is relatively slim. It comes in at 3.2 by 2.6 inches (HD), weighs about 12.3 ounces, and supports 49mm front filters. The inner barrel is polycarbonate and telescopes out for close focus. The outer barrel is anodized aluminum. Ricoh Imaging, the parent company behind the Pentax brand, markets the lens in black and silver. We received the former for review.

The AW badge is an indicator of weather protection; the lens includes six internal seals to prevent dust and moisture from getting inside, along with an anti-smudge SP fluorine coating on the front element. It's a good match for weather-protected cameras from Pentax. I tested the lens with the full-frame K-1 Mark II, but we expect K-3 Mark III owners to look to it as an all-weather macro.

Aside from the knurled metal focus ring, there are no manual controls. A focus limiter switch is a common feature on macro lenses but is not included here. Instead, Pentax added an in-camera limiter function to recent models via a firmware update.

The software-based focus limiter works like a switch, letting you tell the focus to only try and focus close-up or far away when enabled. Getting to it in the K-1 Mark II is a little bit of a pain. The feature is buried on page six of the menu and cannot be assigned to an Fx hot key button, though you can add it to the rear display quick menu. It's worthwhile to use, though, as the K-1 Mark II can hunt to find focus when working at macro distances, especially in its contrast-based live view focus system.

Screw-Driven Focus, Telescoping Form Factor

Autofocus is powered by a screw-drive mechanism, something that seems well out of step with new-to-market lenses, even for Pentax. It has moved to internal focus motors for newer entries like the HD D FA 21mm F2.4 Limited, but swapping to internal focus would call for an all-new optical formula. This HD edition of the 100mm Macro adds an ED lens element to get rid of unwanted false color, but its 10-element/8-group design is otherwise the same as the older edition's 9-element/8-group formula. Indeed, the previous version's optics and basic design trace their origins from the first autofocus edition of the lens, introduced for film cameras in 1991.

There are some pluses and minuses to the approach. The telescoping design means that the lens itself is pretty small when focused on a far-off subject. A deeply recessed front element also means that you're not likely to contend with too much off-angle flare. Mechanically coupled focus, along with a 270-degree throw, make for precise manual control.

On the downside, the 100mm Macro is a noisy lens when focusing; the screw-drive system makes a loud whir. I'd also take caution with on-lens lighting. I like using a set of wireless flashes for a ring-light effect for macros with lenses with internal focus designs and rigid aluminum barrels, but I'd worry about hanging too much weight on the front element, given the telescoping nature. Even so, there's nothing with an internal autofocus motor to consider as an alternative on sale today for the Pentax system.

There are other macros around this focal length to consider for Pentax, but none with autofocus. The Rokinon 100mm Macro (also sold under the Samyang brand) and Irix 150mm F2.8 offer the same 1:1 reproduction ratio, and you can get 2:1 results with the Venus Laowa 100mm F2.8 2x. All three are manual focus only.

The other alternatives are wider-angle but include autofocus: the HD DA 35mm F2.8 Limited is an APS-C lens, but works with full-frame cameras. While it does a great job as a close-focusing standard prime, a short working distance and screw-driven focus system are drawbacks. The same is true for the full-frame D FA 50mm F2.8.

None of these lenses are optically stabilized, but neither is the HD 100mm Macro. Pentax puts in-body image stabilization (IBIS) into its cameras, so you do enjoy effective stabilization with any attached lens. However, for close-up work, you'll need to contend with some shakiness in the handheld viewfinder. Macros with stabilized optics avoid this, but there aren't any available for Pentax cameras.

HD D FA 100mm Macro: In the Lab

I paired the HD D FA 100mm with the K-1 Mark II and Imatest to check its optical performance. The lens delivers the same sharp, clear results as the previous version, notching around 3,300 lines on our test chart at wide-open aperture. It's just as good at narrower apertures down through f/11. You can set the lens from f/16-32 as well, and may find very small f-stops useful to get more in focus at macro distances, but picture quality suffers noticeably due to optical diffraction.

We're happy to see that the field of focus is relatively flat, and the lens avoids any sort of visible optical distortion. It's suitable for technically-minded photography like reproduction work. There is a bit of a visible vignette at f/2.8, but illumination evens out at f/4.

We noticed quite a lot of false color with the previous edition of the lens. The new HD version has improved coatings, but it's the additional ED element inside that proves to be a difference maker. I couldn't spot any false color in photos, even in typical trouble spots like power lines and bare tree branches against a bright sky. Likewise, I couldn't spot any false color in defocused areas of the frame.

The look of the defocused areas of photos benefits from the improved optical formula. I couldn't spot any distracting false color in transitions between the plane of focus and background blur. Highlights show generally soft edges, and are rounded, making for good-looking backgrounds.

A Half-Hearted Update

While we're happy to see the old SMC 100mm F2.8 ED WR get an update in the form of the Pentax HD D FA Macro 100mm F2.8 ED AW, we're disappointed that Ricoh Imaging's engineering team didn't do more. Sidestepping the false color issues exhibited by the previous edition is welcome, no doubt, but the decision to stick with the same fundamental screw-driven, telescoping formula is a detriment.

The lens may seem stuck in time, but it reflects the Pentax system. We saw great SLR macros come out for other brands in recent memory, but third-party options like the Tamron SP 90mm F2.8 never made it to K-mount. It and other macros with internal focus systems offer quicker, quieter focus, and are a bit more practical for handheld work thanks to optical stabilization. Pentax recognized this and developed the stabilized HD 90mm F2.8 Macro for its 645Z medium format camera.

Even though the Pentax HD D FA Macro 100mm F2.8 ED AW isn't an all-new lens, at the very least it solves a real issue with the previous version and does so for the same price, a reasonable $549.95. As we've touched on, there aren't many other options here for Pentax owners. Those who've opted to stick with the system are faced with sporadic additions to the catalog, and, in this case, approaches to lens design that are out of step with current standards.