HD Pentax-DA 35mm F2.8 Limited Macro

Sharpness

Sharpness, or the ability to resolve small details, is an important measure of the performance of a lens. Sharp images let the viewer concentrate on the composition, color and light. On the other hand, soft images (except when looking that way on purpose) distract the viewer and decrease the perceived quality of the picture.

Like 50mm lenses, 35mm are usually "safe" designs. It's pretty easy to create a good 35mm lens. Both focal lengths use variations of the "double Gauss" design, with usually 6 or 7 glass elements. The DA 35mm macro Limited, however, uses a whopping 9 glass elements, with a different optical formula.

There are many ways to evaluate sharpness. Some are quantitative, such as counting the number of lines per millimeter that can be resolved, while others are comparative, such as using a standardized scene to pit lenses against one another. The latter is the favored method at Pentax Forums.

Test Setup, Star Chart

In order to evaluate sharpness, we use a standard test chart (or "Star chart") that can be used to compare lenses to one another. The general rule is that the distance from the lens to the test chart must be 100 times the focal length of the lens. For our 35mm lens, this means a distance of 3.5 meters. The test is not designed to show how good a lens can be. On the contrary, it is a stress test designed to put the lens at its limits to show where it falls short. The test shows the apertures where the lens performs best, and makes it possible to compare to another lens.

Our test has the star chart placed successively at the center, edge and corner of the lens' field of view, testing all apertures each time.

Resolution is obviously dependent on the sensor used. For this test, we used Pentax's current top-of-the-line APS-C sensor found in the K-3.

New Pentax DSLR bodies include the ability to disable anti-aliasing, a very useful feature that allows higher resolutions to be reached. However, the nature of our sharpness test and the pattern of the test chart means that, with anti-aliasing totally disabled, moiré is likely to appear. In order to strike the best balance between sharpness and moiré reduction, the anti-aliasing simulator of the K-3 was activated, but set at the "Low" setting.

Test Results, center at 35mm

The following images showcase the results at all apertures for the center area. We used the DA L 35mm F2.4 lens as a benchmark for comparison. Both lenses have the same focal length, and the cheaper, DA L lens performed admirably in its own test. You can click on images to see full resolution crops.

	HD DA 35mm macro	SMC DA L 35mm
F2.8
F4
F5.6
F8
F11
F16
F22

Center sharpness is where all lenses are expected to shine, and both our test subjects performed admirably. At wider apertures, the Limited macro has a visible advantage, and both lenses offer good resolution. Things even out at F5.6 and the lenses are similar as the aperture closes. What is impressive is that the Limited macro does not improve a lot as the aperture closes: it's already excellent wide open, leaving little room for improvement.

Test Results, edge at 35mm

The following images compare both lenses for edge sharpness. You can click on images to see full resolution crops.

	HD DA 35mm macro	SMC DA L 35mm
F2.8
F4
F5.6
F8
F11
F16
F22

The lenses are almost impossible to differentiate on the edges. The DA L appears to have a small advantages at wider apertures, which can be surprising at first. This is in line with what we observed in the DA L review, where we hypothesized that the design of the cheaper lens, being based on a Full Frame lens, gives a slight advantage in the corners.

Test Results, corner at 35mm

The following images compare both lenses for corner sharpness. You can click on images to see full resolution crops.

	HD DA 35mm macro	SMC DA L 35mm
F2.8
F4
F5.6
F8
F11
F16
F22

The corner again shows an advantage for the DA L lens, at apertures wider than F11. Both lenses actually perform well, and comparisons between the center and the corner do not show the tremendous differences that some lenses exhibit. Still, the DA L lens shows consistently sharper results than the Limited macro.

Real-life test

Test charts never tell the whole story. The following images illustrate the performances of the lens with a real-life test subject with a lot of detail. We used close focus to differentiate with the star chart tests, which are performed at a significant distance. Click on the images to open a new window with the full-resolution files.

Note that while bokeh will be evaluated later in this review, the images below show a good example of what to expect.

F2.8
F4
F5.6
F8
F11
F16
F22

Summary

The HD DA 35mm Limited macro is a sharp lens, no doubt about it. Especially in the center, it shows a high level of detail at all apertures. This is desirable (and expected) for a macro lens. On the edges and corners, it is still very sharp, but is slightly outperformed by the less expensive DA L 35mm F2.4. These findings are in line with what was observed during the cheaper lens's review.

A macro lens is expected to deliver consistent results at all apertures and across the frame. In this regard, our test lens does not disappoint. It might not be THE sharpest lens out there, but it's certainly close.

Test patterns and controlled tests never tell the whole story. Be sure to check out the sample gallery to make up your mind!