Irix 15mm f/2.4 Blackstone Samyang XP 14mm f/2.4
£574/$675 A beautifully turned out manual-focus prime £899/$999 A delightfully premium manual-focus lens
he Irix 15mm f/2.4 manualfocus prime is available in Firefly and Blackstone editions. The optical path is identical in both lenses, but the pricier Blackstone has better build quality, with a metal barrel and an extra weather-seal. It also gains engraved markings filled with Uv-reactive paint.
Built-in electronics enable full communication with the host camera, as per the Samyang lenses on test. The focus scale has markings for both hyperfocal distances and depth of field limits for apertures of f/8, f/11 and f/16, and the tactile focus ring is supplemented with a focus locking ring. Quality optics include three aspherical elements, two ED (Extra-low Dispersion) elements and four HR (High Refractive) elements, along with neutrino coatings.
TPerformance
It’s the sharpest lens in the group at the centre of the frame, although levels of sharpness are more average towards the edges and corners. Colour fringing and distortion are minimal, and there’s good resistance to ghosting and flare.
Sharpness
Centre-sharpness is exceptional, however, there’s quite a drop-off towards the corners of the frame.
Fringing Distortion
There’s little barrel distortion and the Irix scores particularly well in close-range lab tests. amyang’s range of ‘XP’ manual-focus lenses aims for premium-grade optical design and construction. Compared with the Irix 15mm, the Samyang gives a slightly wider viewing angle on full-frame cameras, at 114 rather than 110 degrees.
This lens has 18 optical elements, including two aspherical, one hybrid aspherical, two extra-low dispersion and three high-refractive index elements. Build quality feels solid, but there are no weather-seals. Handling is superb, with a fluid feel to the action of the rubberized focus ring, although the focus distance scale lacks depth of field markers. Built-in electronics enable aperture control from the camera, and illumination of the focus-assist lamps in the viewfinder.
SPerformance
Centre-sharpness isn’t as good as from the Irix when shooting at the widest aperture of f/2.4, but sharpness across the entire image frame and right into the corners is impressively consistent. Stop down a little to f/4 or narrower apertures and sharpness becomes very good indeed.
Sharpness
Sharpness drops off a fair bit at f/2.4, but this isn’t generally an issue when it comes to landscape photography.
Fringing Distortion
Barrel distortion is more noticeable than from the Irix manual-focus prime.