Irix 15mm f/2.4 Review: Surprisingly Good Optics


Irix may not be the most obvious make of camera lens, but they are designed by Switzerland-based TH Swiss and put together in Korea to keep down costs. Boasting great optics, the lens comes in two varieties of the ‘Firefly’ and ‘Blackstone’ with basically different outer shells at different price points.


To start with the two versions of the lens have the same optics, but the Firefly version is made from solid plastics, while the Blackstone is made from magnesium and aluminum alloy. Both are manual-focus 15mm at f/2.4 and more or less the same lens, but the Firefly version has a rubber focus ring and has a plastic outside, costs less and weighs less.

Currently, the lens works with Canon and Nikon bodies. The Canon version has all the correct contacts, as with the Nikon and works in all modes. For the nitty-gritty specifications, the lens has 15 elements in 11 groups, with 2 aspherical elements, 2 extra-low dispersion elements, 3 high refractive-index elements, and a ‘neutrino’ multicoated element. There are also nine rounded diaphragm blades with an aperture range of f/2.4 to f/22. The angle of view is 110 degrees on a full frame body, which this lens is optimized for and a 0.8 feet closest focusing distance. Up front is a 95mm filter thread, on top of which is a petal-shaped lens hood, with a nice little aperture to get at the filters.


The outside of the lens is quite sparse with the focusing ring and a distance scale below it. The rear of the lens also has a 30 × 30mm gelatin slot for good measure. Everything here weighs in at 641.5g, not too heavy, not to light. Everything in the package comes in a nice little carry case and metal tin provided as a nice display box.

At least on the surface, the Irix 15mm f/2.4 up to now has the basic essentials to be a good quality wide-angle lens. So, let’s dive in and see how it performs in reality.

Image Quality

Straight out of the box, the Irix 15mm f/2.4 delivers sharp images and crisp colors allowing in loads of light with its wide aperture. As per usual with the aperture, stopping down just a little provides the sharpest images around f/4, but results are surprisingly good across the range. There is a tiny bit of softness in the corners when fully wide-open, but as a rough comparison, it’s on the same levels as the Nikon 14-24mm f2.8.


As to be expected with the very wide-angle lens, there is some vignetting apparent when fully wide open at f/2.4. Stopping down to f/2.8 cures things, but with very wide-angle images a touch of vignetting is usually added in postprocessing to replicate this effect. However, it’s better to have the option with a totally clean image than the other way round. Chromatic aberration is also minimal across the range, as is ghosting and flaring which only becomes a problem when the sun is in your face or in extremely bright light. The only problem I found with this lens is when postprocessing in that there was no lens profile to set up any corrections in Lightroom. This is just one of the downsides of a third party lens.

There is little to no color fringing, even without a lens profile, which in itself is very good. Lastly, the background blur or bokeh is very good. Nice and smooth transitions of colors, without being too busy. It’s not the most fantastic bokeh, but it’s extremely respectable for how wide it can go. The lens also provides some nice sun stars in bright sunlight when completely stopped down without the usual distracting flaring. This does add a nice element to any daylight image.

This isn’t a straight up macro lens, but when you get to the closest focusing distance and crop down your subject, everything is lovely and sharp with plenty of contrast. Even when fully open at f/2.4 the results are very good.

In total it’s hard to find any fault with the sharpness of this lens across the aperture range. When wide open images come out with lots of contrast and sharpness and give the feeling that the lens could give competitors a definite run for their money.

How Does It Compare?

There are quite a few competitors to the Irix 15mm f/2.4. This means more choice for us as consumers at different price points. Firstly, this is a full frame lens so crop sensor people may be better off looking at the Canon 10-18mm or the Nikon 10-24mm, which both have the benefit of being zoom lenses.

Keeping on the zoom theme, the Canon 11-24mm is one of the best contenders for Canon users at this width. Fantastic optics but also quite pricey. For Nikon users, the 14-24mm f/2.8 G is a good workhorse which is slightly wider but is also a big beast of the thing. Optically the Irix 15mm f/2.4 is as good as these lenses and really crushes older primes for sharpness.

 Irix 15mm f/2.4 Canon 11-24mm f/4
Elements 15 elements in 11 groups 16 elements in 11 groups
Aperture f/2.4 to f/22 f/4 to f/22
Filter thread 95mm Rear attached only
Weight 641.5g 1166g


Third-party lenses have definitely come a long way in recent years. The Irix 15mm f/2.4 is definitely a great wide-angle prime, which produces some extremely sharp images with ultralow distortion and vignetting. The outcome of the results for the TH-Swiss produced lens was surprising and it goes to show that we have more options now for lens choice than ever before, with most producing supersharp results.

If the Irix 15mm f/2.4 is anything to go by, it is hoped that more primes are produced from this company, as this version is well priced and if it wasn’t for being an unfamiliar brand, it could easily measure itself up to its competitors any day. Definitely a recommended lens option if you want a medium priced, ultrawide prime lens.

Very sharp
Solid construction
Little distortion

Only manual focus
Wide filter thread

DealsAmazon $424
B+H $675

Review Breakdown
Design 90%
Performance 90%
Lens 100%
Optics 100%
Price 90%

The Review


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