Pentax-D FA 100mm F2.8 Macro WR

General Image Quality

Macro lenses create high expectations for their users. Extreme sharpness, beautiful colors and smooth bokeh are expected, and anything less than excellence is seen as a failure to deliver. In the following pages will look in detail at every measurable parameter, but for the moment we will consider those subjective elements that can make or break an image.

Field of View

100mm has been seen as a natural focal length for macro in the film era. The field of view is obviously narrower with a digital APS-C sensor. Photographers used to film (or full frame in general) might find it a bit tight. On the other hand, users knowing only the APS-C format are likely to find it perfectly natural, either for macro or as a short tele lens.

Color and Contrast

The macro world is full of rich colors and brightly saturated subjects. Pentax cameras, especially when used with the "Neutral" setting, produce JPEG files that are perfectly usable but do not deliver the punch that some have come to expect from their images. Because of this, images often benefit from a few adjustments in post-processing that can bring out the best they can offer. The following comparison shows an uncorrected JPEG as produced by a K-3, and the same image adjusted in Lightroom. The corrections made include slight adjustments in contrast and saturation, but nothing else was changed. The image was originally shot with the Neutral setting, at f11, 1/1600 seconds, ad ISO 800.

Although the first image is usable as is, the second one is probably more in line with what people generally expect for such a subject. It is of course possible to fine-tune the image parameters in-camera to obtain JPEGs perfectly tuned to every user's preferences.

It must be noted that, when used as a tele lens with regularly-sized subjects, the lens does not require regular adjustment of its images. Quite the contrary, as the images produced by the 100mm macro WR have a rendering that make them easy to spot when browsing an image gallery.

Metering and Exposure

The lens exposes well in most circumstances, whether on a K20D or a K-3. We found exposure to be generally reliable at all apertures. Of course this is influenced by the scene and the type of exposure mode selected, which are independent of the lens itself.

Lens Correction and EXIF Data

The 100mm macro WR is a lens made for digital, and as such it includes all the necessary data for modern camera bodies to apply in-camera lens correction when required. Vignetting, diffraction, aberration, and distortion can be adjusted in-camera.

EXIF data is complete and accurate, and Pentax camera bodies are able to record every relevant parameter into the file.

On-Board Flash Usage

The following image illustrates the absence of shadows when the on-board flash of a K-3 is used, even if the lens is set to its closest focus distance.

Flash coverage

The story is different if the dedicated hood is used, however. When focusing at close distances, a significant shadow is cast.

Flash coverage with hood

In the following section we will look at the sharpness measurements.


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