Irix 15mm f/2.4 Review

May 4, 2017 | Mark Goldstein | |

Introduction

The Irix 15mm f/2.4 is a manual-focus ultra-wide-angle prime lens for 35mm full-frame DSLR cameras (Canon EF, Nikon F and Pentax K mounts). It features 15 lens elements in 11 groups, an aperture range of f/2.4-f/22 and a 9-bladed circular diaphragm for smoother bokeh blur in out of focus areas. The Irix 15mm f/2.4 comes in two versions, Firefly and Blackstone, with the latter offering a more durable aluminum/magnesium alloy body and engraved fluorescent markings. The Irix 15mm f/2.4 Firefly costs around £399 / $400, and the Irix 15mm f/2.4 Blackstone costs around £569 / $600.

Ease of Use

With a maximum diameter of 114mm and a length of 100mm, the Irix 15mm f/2.4 is an ultra-wide-angle fixed focal length optic that's well-suited to full-frame DSLRs like the Canon EOS 5DS R that we reviewed it with. Weighing in at 608g for the Canon version, it's quite heavy, making this lens better suited to life on a tripod than to being used hand-held. It is also compatible with APS-C cameras, where it will produce a 22.5mm equivalent focal length.

Irix 15mm f/2.4The Irix 15mm f/2.4 lens mounted on a Canon EOS 5DS R

Irix 15mm f/2.4The Irix 15mm f/2.4 lens mounted on a Canon EOS 5DS R

Irix 15mm f/2.4The Irix 15mm f/2.4 lens mounted on a Canon EOS 5DS R

Irix 15mm f/2.4The Irix 15mm f/2.4 lens alongside a Canon EOS 5DS R

Two versions of the Irix 15mm f/2.4 lens are available, differing in their build quality. The standard Firefly version that we reviewed is made of lightweight composite plastics, covered in an anti-slip rubber coating with printed markings. The more expensive Blackstone version has a aluminum/magnesium alloy body for extra durability, plus engraved fluorescent markings which reflect UV light, making it easier to use in the dark. Note that the Blackstone version is slightly heavier.

Irix 15mm f/2.4The side of the Irix 15mm f/2.4 lens

Irix 15mm f/2.4The side of the Irix 15mm f/2.4 lens

The Irix 15mm f/2.4 has 15 lens elements in 11 groups, including 3 high refractive lenses, 2 ED lenses and 2 aspherical lenses, and a 9-bladed rounded diaphragm helps to provide smooth bokeh blur.

With no need for a zoom ring, the manual focusing ring spans a significant width of the lens barrel and is exceptionally smooth to operate, complete with a useful hyperfocal scale and a handy infinity click-stop feature.

Irix 15mm f/2.4The front of the Irix 15mm f/2.4 lens

Irix 15mm f/2.4The rear of the Irix 15mm f/2.4 lens

The Irix 15mm f/2.4 lens has a a convenient focus lock mechanism, activated by a slim ring that sits between the end of the lens and the focusing ring, although we did find it stiff to operate.

Irix 15mm f/2.4The side of the Irix 15mm f/2.4 lens

Irix 15mm f/2.4The side of the Irix 15mm f/2.4 lens

There’s no optical image stabilisation, but the lens’ very short focal length and fast maximum aperture mostly alleviate the need for it. A removable metal petal-shaped lens hood is fitted, which means that you can use a front filter system with this lens. You can alternatively choose to fit rear gelatin filters.

Irix 15mm f/2.4The Irix 15mm f/2.4 lens in-hand

Irix 15mm f/2.4The Irix 15mm f/2.4 lens with the supplied hood fitted

Both versions of the Irix 15mm f/2.4 have the same level of weather-sealling against dust and moisture, with two seals around the focus ring and one on the bayonet mount.

The Firefly version of the Irix 15mm f/2.4 includes a soft lens pouch, while the Blackstone version ships with a hard lens case. Both versions include an extra rear lens cap.

Focal Range

The 15mm focal length gives an angle of view of 110 degrees on a 35mm full frame sensor.

 Irix 15mm f/2.4Field of view at 15mm

Chromatic Aberrations

Chromatic aberration (purple fringing) isn't that much of an issue with the Irix 15mm f/2.4 lens, only appearing as purple or green fringing in a few of our test shots, as shown in the example 100% crops below.

Irix 15mm f/2.4 Irix 15mm f/2.4

Light Fall-off and Distortion

Light fall-off is noticeable wide open at f/2.4, though this is to be expected for such a wide-angle lens and can easily be corrected in Photoshop. Stop down to f/5.6 and the vignetting is already less prominent, but it is still visible when shooting pale scenes that fill the frame. Barrel distortion is quoted by Irix as being a minimal 2%.

Irix 15mm f/2.4Light fall-off at 15mm

Macro

A 25cm / 0.82ft minimum focus distance makes the lens useful for shooting reasonably close subjects. This image is uncropped and shows how close you can get to a Compact Flash card.

Irix 15mm f/2.4Close-up performance

Sharpness

In order to show you how sharp this lens is, we are providing 100% crops on the following page.

Entry Tags

review, samples, photos, jpeg, nikon, jpg, camera, dslr, canon, pentax, 5ds r, f2.4, irix, Irix 15mm f2.4 photos, irix 15mm, Irix 15mm f2.4, Irix 15mm f2.4 review

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