Amanual focus, full-frame ultra wide-angle lens that promises a quality performance at an attractive price Irix 15mm f/2.4 Blackstone
› Prices Blackstone £670, Firefly £479 › In the box Hard lens case, two rear lens caps, metal box, lens hood › Format 35mm full-frame › Mount Nikon F (tested), Canon EOS › Autofocus No › Construction 15 elements in 11 groups › Special lens elements 3x high refractive index, 2x extra low dispersion, 2x aspherical › Coatings Neutrino › Filter size 95mm front fitting, 30x30mm gelatin rear fitting › Aperture range F/2.4-22 › Diaphragm Nine blades › Internal focus Yes › Manual focus Yes, with focus lock › Minimum focus 28cm › Focus limiter No › Distance scale Yes › Depth-of-field scale Yes, hyperfocal setting › Image stabilizer No › Tripod collar No › Lens hood Supplied, bayonet fit with sliding window for access to polariser › Weather-sealed Yes, Blackstone has four rubber seals, Firefly three seals
IRIX LENSES, DESIGNED in Switzerland and built in Korea, combine classic lens design, the latest optical design technologies and maximum functionality to bring photographers manual focus lenses with a unique feel and usability. Three manual focus lenses are in the current photo range, and the 11mm f/4 ultra wide and the 150mm f/2.8 macro – we have tested both lenses in the previous two issues. One innovation Irix has brought is that its two ultra wide-angle lenses are available in two versions, called Blackstone and Firefly. The optical design of both versions is identical but there are physical differences.
The Firefly variant has three physical seals protecting the camera mount and focusing mechanism from dust and water splashes. The focusing barrel is rubber gripped and the lens is lighter. The Blackstone version is the premium lens with a more durable aluminium alloy body, four rubber seals for protection from front and sideways water splashes and a machined focusing barrel. The lens’ engraved markings are fluorescent, too. We had a sample of the Blackstone 15mm f/2.4 for this test. (In PN 69 we tested the 11mm f/4 Firefly). Build quality is impressive and this is a solid-feeling lens that makes
a great partner for the Nikon D850 I used for the test. Balance is good and the knurled focusing ring is within easy reach with the supporting left hand. On our sample, the focusing barrel had a smooth, taut travel so didn’t move when the hand was taken away. However, Irix has provided a focus lock – this is the thin ring at the front of the lens. The minimum focus of 28cm is achieved with half a rotation of the focus barrel and the lens passes through the infinity index which is click-stopped so you know you’re at infinity without looking. Focusing through that infinity comes in useful when perhaps shooting in very cold
or hot conditions when infinity focus might shift very slightly. An excellent depth-of-field scale is provided – engraved like the distance marking – and hyperfocal indexes for f/8, f/11 and f/16 are provided. An infrared index is also provided. Optically, this lens performed impressively. You get decent sharpness at f/2.4 and f/4 at the centre while edges were okay, but there is a significant lift in edge performance from f/5.6 and better still, at f/8, where sharpness across the frame was very good. F/8 and f/11 were this lens’s best overall aperture settings, with diffraction impacting on f/16 and f/22. Vignetting was evident at the wide apertures and this went by f/5.6. There were signs of fringing at the edges but this wasn’t by any means severe, and both issues were resolved in editing. It’s difficult avoiding the light source with such a wide lens, but while direct aiming into the sun produced some flare spots it wasn’t an issue and image contrast remained high. WC
› Dimensions 114x100mm › Weight Blackstone Nikon fit 625g, Firefly Nikon fit 581g
Test images were shot using a Nikon D850 mounted on a Benro tripod and shutter fired with the camera's exposure delay mode. Raws were processed in Lightroom and exam- ined on-screen at 100%.
PROS Build quality, optical showing at f/8 and f/11, fast aperture, focusing action CONS Edge quality at wider apertures, big filter thread If this lens appeals, the decision is whether to go for the Firefly version and save £191 and a few grams, or go for themore rugged version with engravedmarkings. Either way, you can’t go wrong because optically this is a very capable lens. Verdict I really enjoyed using the Irix 15mm f/2.4, partly because I like the drama you get with ultra-wide lenses – especially when you get in close – and partly because this lens is good to use.
Issue 70 | Photography News 57
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