IRIX 15mm f/2.4 BLACKSTONE 03

It’s feature-rich for a manual-focus lens and boasts top-notch build quality and handling

Irix offers a 15mm f/2.4 in two different versions, the Firefly and the Blackstone. The optical path is identical in both, but the pricier Blackstone has better build quality, with a metal, rather than plastic barrel, and an extra weather-seal. The Blackstone also has engraved markings filled with Uv-reactive paint, and comes in a hard case.

Although it’s a manualfocus lens, it’s not lacking in features. Built-in electronics enable full communication with the host camera body, so you can control the aperture from the camera and shoot in the full range of shooting modes without restriction. Illumination of the camera viewfinder’s focus confirmation lamp is also enabled, and lens-based EXIF data is recorded with images.

Focusing is done via a typically long-travel manual focus ring, which has an infinity position click, as well as markings for both the hyperfocal distances and depth of field limits for apertures of f/8, f/11 and f/16. Quality optics include three aspherical elements, two ED (Extra-low Dispersion) elements and four HR (High Refractive) elements, along with neutrino coatings.

Performance

It’s the sharpest lens in the whole group at the centre of the frame, but sharpness is more average towards the edges and corners. Colour fringing and distortion are minimal, but coma and astigmatism give irregular shapes to pinpricks of light when shooting wide-open.