Irix 150mm F2.8 Macro Review

General Image Quality

On the following pages we will look in detail at every measurable performance parameter, but for the moment we will consider those subjective elements that can make or break an image.

Field of View

On full frame, 150mm is in the realm of short tele. For general photography, it will be a good focal length for portraits outside, or in a very large room. It will be too tight for portraiture in most standard rooms. For macro, for a given working distance the field of view will of course be narrower. This grants the photographer a longer distance between the camera and subject for a given magnification. This is often useful, especially with live subjects, or in general to avoid casting shadows or disturbing the scene.

On APS-C, the field of view is of even narrower. The effective focal length is 225mm, which is straight into tele territory.

Color and Contrast

Irix colors leave nothing to be desired. This was true for their two wide angle lenses, and holds for this new 150mm.

Colors are richly saturated and nicely contrasted. This is particularly useful for macro.

Metering and Exposure

We experienced few exposure errors with the lens, except sometimes in macro settings with white subjects. This is not unique to this lens: macro scenes tend to have high dynamic range. We note that a certain number of underexposed events occured when using the lens on an APS-C camera and while setting the aperture at F2.8 or F32.

Starbursts

Starbursts wide open are essentially absent. However, at smaller apertures the Irix 150mm Macro produces superb starbursts. The number and shape of the rays enhance the image without becoming distracting. This is a nice perk of this lens.

F2.8
F8

Lens Corrections and EXIF Data

As with all third-party lenses, the Irix 150mm Macro does not benefit from in-camera corrections.

EXIF data are still complete and accurate, and Pentax camera bodies are able to record every relevant parameter into the file. Note that it is up to your software to properly decode these data when an image is viewed on a PC. The lens' version (Firefly or Blackstone) is of course not recorded, only the focal length.

On-Board Flash Usage

The K-1 does not have an on-board flash. When testing on a K-3 (an APS-C DSLR), the lens created a strong shadow, as is to be expected given the size of the lens.

User Report

The Irix 150mm is a physically impressive lens. With a diameter larger than the DA* 60-250mm and a length slightly shorter, it dwarfs many other lenses, especially macros which tend (at least when coming from Pentax) to be rather small.

The Irix still handles well, and can be handheld if so desired. The tripod foot can get in the way but one gets used to its presence. It does not prevent the use of the focus ring.

The biggest challenge is managing the razor-thin depth of field, which can cause trouble when focusing. While using a tripod and shooting a stationary subject, this is not a problem, and the lens offers a high level of accuracy. For handheld, non-macro scenes, nailing the focus precisely can become challenging.

The lens communicates well with the camera and the workflow is natural.

150mm is an interesting focal length for macro. The extra working distance is useful most of the time. Since the depth of field is influenced more by the magnification than the focal length at macro distances, the longer focal length does not create a shallower DOF. The same cannot be said for non-macro scenes, there subject isolation will be enhanced.

In the next sections we will look at the optical performances of the Irix 150mm F2.8 Macro.