The Irix 15mm f/2.4 Blackstone Lens
This beautifully-designed and sharp little wide-angle lens was a huge surprise to this long-time Canon lens user. The Irix 15mm f2.4 lens is offered in two models: the Blackstone (aluminum and magnesium alloy housing, weather-resistant exterior with inner seals for dust and moisture protection, engraved focus distance and depth of field scales, an anti-scratch finish, and hardshell case) and the Firefly (lightweight plastic exterior construction, rubber focus ring, printed focus distance and depth of field scales, and soft case). The optics of the two models, however, are identical. I was fortunate to recieve the Irix 15mm Blackstone mode with Canon mount.
Irix 15mm f/2.4 Blackstone Lens Features
- Wide-angle prime lens with Canon EF-mount (also available for Nikon and Pentax) with 15mm focal length for full-frame DSLRs and 24mm equivalent for APS-C.
- Aluminum and magnesium alloy housing and weather-resistant exterior, sealed against dust and moisture intrusion, anti-scratch finish, sports engraved focus distance and depth of field scales with fluorescent UV paint for high visibility.
- A Neutrino coating has been applied to limit lens flare and ghosting for improved contrast and color fidelity.
- Manual focus design is benefitted by a positive focus lock mechanism to secure your focus position at any point to limit unwanted shifting of focus.
- A hard click stop indicates the infinity position on the focus ring for easy use in low-visibility conditions.
- Large depth of field scale benefits using hyperfocal and pre-focus techniques.
- 95mm-diameter filter threads and the rear of the lens accepts 30 x 30mm cut gel filters to lessen the likelihood of vignetting
- Rounded nine-blade diaphragm contributes to smooth bokeh.
- Minimum focusing distance 11 inches (28centimeters).
Bodie Island Lighthouse with approaching evening clouds, Cape Hatteras National Seashore, North Carolina USA. Canon EOS 5D Mark IV, Irix 15mm f/2.4 Blackstone Lens, 1/10 second @ f/16, ISO 100
The Irix 15mm f/2.4 Blackstone Lens In the Field
The sharpness of this lens matches any of the Canon wide-angle lenses I regularly use, which includes the primes and the zooms. I must admit this was quite a (pleasant) surprise. When used wide open at f/2.4, the image center was acceptably sharp but the corners were noticeably soft. After stopping down to f/4, however, the entire image was impressively sharp from corner to corner. There was also noticeable darkness in the corners when I used it wide open but was was mostly gone by f/2.8 and completely gone by f/4. So it’s obvious that f/2.4 is not a strong aperture in which to work. For landscape photographers, this is a non-issue. At f/16, an aperture landscape photographers are much more likely to use, the image sharpness was every bit as good as my Canon 11-24mm at the same focal length.
Distortion was minimal and glare and ghosting when shooting directly into the lens was mostly under control. I wouldn’t say it was exceptional but it was definitely acceptable in this regard (no better or worse than some wide-angle lenses costing two or three times as much).
The one item that I’m sure will cause many photographers to pass on this lens is the lack of autofocus. For street photography, this might create a slight challenge to those photographers who grew up exclusively on autofocus, but to the older guys and gals, it will be no problem at all. Still, I see this as a landscape lens and I actually prefer to use manual focus anyway when capturing landscape images. The focusing ring is smooth with just the right amount of friction when turning. This lens also has a focus lock ring which allows you to maintain the selected distance by adjusting the friction ring to the locked position to keep the distance unchanged.
For filters, the Irix 15mm f/2.4 Blackstone lens gives you two options. The size of the front element is 95mm, which is an odd filter size. But there’s also a slot near the lens mount that allows a 30mm x 30mm gel filter, which not only ensures you won’t get any vignetting with a front filter but is also a much cheaper filter option as well.
I can honestly say that I am pleasantly surprised at both the optical performance and the build quality of the Irix 15mm f/2.4 Blackstone lens. I can only speak for the Blackstone model and not the Firefly, however, but I understand the the optical quality is the same for each. The sharpness of this lens is on par with any wide-angle lens I’ve ever used with little distortion and only a small amount of vignetting at f/2.4. I had no problems with chromatic aberration, and when I aimed the lens into the sun, ghosting and flare were minimal. Some photographers might balk at the lack of autofocus, but for landscape photography – the application for which this lens is obviously meant – autofocus is not even a necessary feature. If you want a truly excellent wide-angle prime lens at a very reasonable price, this lens fits the bill.
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