- Very good sharpness
- CA well corrected centrally
- Widest rectilinear lens available
- Very little chance of flare
- Moisture and dust resistance
- Well priced
- Some edge CA
- Manual focusing via the camera screen very difficult
It is clear from the moment we receive the classy packaging that this Irix lens is seriously aiming to compete with the best. Nestled within the unusual tin box lies the widest rectilinear (nearly) lens on the market, an incredible 11mm f/4, suitable for full frame Canon, Nikon and Pentax DSLR cameras. There is a choice of Blackstone and Firefly versions, both optically identical and both weather sealed, and here we try out the lighter Firefly version on a Canon EOS 5DS R body. This should be interesting, so let’s look a little more closely at what we have.
Handling and Features
A huge plastic snap-on lens hood protects the equally huge, bulbous front element. When in use, this vulnerable front element is protected from impact and from flare by the efficient looking petal lens hood. The hood is fixed and a part of the lens barrel so there is no possibility of using filters. In any event, keeping feet and the photographer’s shadow out of the images is something to watch and a filter mount would almost certainly intrude on the field of view.
This is a manual focus lens and just behind the hood is a locking ring that can be used to fix the focus at a desired position. Immediately behind this is the focusing ring, wide enough to give a good grip and very smooth in operation. On the Firefly version, this also has a raised area to assist grip even further. The distance scale is marked in feet and metres, from infinity down to 0.275m, or 0.9 feet. This is close, but the lens is so wide that initially, it is quite surprising how much is actually included in the frame.
An unusual feature of the distance scale is the inclusion of a Hyperfocal Distance scale. Just lining up the aperture in use with the focus index mark sets the lens to the hyperfocal distance for that aperture. This is a simple and ingenious thought that will be very helpful when seeking to maximise depth of field. It is also useful to set a “snapshot” setting as focusing the lens by eye is well nigh impossible. Modern AF screens do not have the acuity to see the point of focus, and many eyes won’t either. The only real way to focus is to set the scale to the estimated or measured distance. Fortunately, the enormous amount of depth of field allows this to be a practical way to achieve good focus.
There is also a very clear depth of field scale, and an innovative light click stop at the infinity point of the focusing ring, so this can be set even in poor light by feel. The Firefly version of the lens has painted markings, but the more expensive Blackstone has engravings filled with luminous paint, a feature that is really useful in low light.
Finally, the position of the focusing scale can be adjusted as well. Just behind the front of the lens, there is a small access point and by screw adjustment, the position of the focusing scale can be fine tuned for maximum accuracy.
Even the original 15mm f/3.5 lenses of the early 1970s used aspheric elements, so it is no surprise that this 11mm f/4 lens has an optical construction of 16 elements in 10 groups and includes 4 HR (High Refractive Index), 2 ED (Extra Low Dispersion) and 3 Aspherical elements. Neutrino coating helps make this possible, the Irix version of nano coating. 9 rounded diaphragm blades result in a more circular aperture, for improved bokeh.
This is a chunky, heavy lens, the Firefly version weighing in at 783g. There is sealing against dust and moisture, another welcome feature in any lens.
The biggest handling issue, if it is an issue, is likely to be focusing. As mentioned, using the viewfinder or Live View is not really possible, so measuring or estimating distances is a way forward. For most outdoor shooting selecting the hyperfocal distance for the aperture in use works very well. After that, just shoot away, with no need to worry about any further focusing.
Other than that, if you like wide angle lenses then this one is so wide that it opens all sorts of creative possibilities. The wide breadth of sweeping landscapes is incredible, but do watch that there is a strong foreground interest to avoid wide swathes of empty space. It is also necessary to get in close, closer, closer….and still the subject can be too small. The sample images of buildings were shot at incredibly close distances to fill the frame, and, of course, this presents all sorts of challenges regarding perspective and the “drawing” of the straight lines. Things look normal but very wide when the camera back is parallel to the subject, but tilt it even slightly and we enter a new world.
Firefly & Blackstone Comparison Table
Firefly and Blackstone versions use the same optics and the same precision, but this table, from the Irix website, summarises the differences.
Looking at sharpness, the centre starts off as very good at f/4, becoming excellent at f/5.6 and f/8. Results are still very good at f/11, falling to good levels at f/16 but becoming quite soft at f/22.
The edges are good at f/4, very good at f/5.6 and f/8, good at f/11, becoming soft at f/16 and very soft at f/22.
Irix 11mm f/4 MTF Charts
How to read our MTF charts
The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges.
The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance.
CA (Chromatic Aberration) is not easy to correct in such a wide lens, but Irix has done a good job. Centrally, CA is well held to under half a pixel. At the edge CA is visible, but this can be tackled in software. A good result.
Irix 11mm f/4 Chromatic Aberration Charts
How to read our CA charts
Chromatic aberration (CA) is the lens’ inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.
Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimise the problem, hence they usually cost more.
Absence of flare is highly creditable. Even into the sun, there are no artefacts and the images display good contrast, diminished slightly but not significantly. Considering the very wide field of view, this makes the lens absolutely usable in all lighting conditions without fear of ghosting effects.
There is -3.70% barrel distortion, hardly surprising. That measures slightly higher than the Irix claim of -3.13%. However, we expect barrelling from ultra wides so our eyes will not find that too disconcerting. Again, the distortion can be tacked in software if desired.
Bokeh is almost not a consideration with an 11mm lens. Unless really sought after, out of focus backgrounds are not the norm and they can look a little odd. The ultra-wide edges when way out of focus look smeared and this is probably not the way to use this lens.
Despite the huge challenges in making a lens of this type, Irix has overall done a splendid job of it, the quality is definitely there and it shows.
Car Interior | 1/80 sec | f/8.0 | 11.0 mm | ISO 200
Close Up Perspective | 1/250 sec | f/8.0 | 11.0 mm | ISO 200
Dungeons And Dragons Group | 1/60 sec | f/5.6 | 11.0 mm | ISO 6400
Flare Test Against The Light | 1/250 sec | f/8.0 | 11.0 mm | ISO 200
Vast Depth Of Field | 1/40 sec | f/16.0 | 11.0 mm | ISO 200
Bokeh At F4 | 1/500 sec | f/4.0 | 11.0 mm | ISO 200
Bokeh At F11 | 1/60 sec | f/11.0 | 11.0 mm | ISO 200
Bokeh At F22 | 1/15 sec | f/22.0 | 11.0 mm | ISO 200
|Angle of View||126°|
|Filter Size||No Data|
|35mm equivalent||No Data|
|Internal focusing||No Data|
|Maximum magnification||No Data|
|Box Contents||No Data|
Value For Money
The Irix 11mm f/4 Firefly lens is priced at around €635, with really nothing else to compare it with. There are 10mm and 11mm rectilinear lenses, but all for APS-C format.
The nearest competitors might be the 14mm lenses. Here we have the Samyang 14mm f/2.8 ED AS IF UMC(£329/$493), Samyang 14mm f/2.4 AE XP (£899/$1348), Canon EF 14mm f/2.8 L II USM (£2149/$3223) and the Nikon 14mm f/2.8 D AF ED (£1389/$2083).
For its unique position as the widest rectilinear lens and the high quality of the images it produces, the price tag seems very reasonable.
What an exciting lens the Irix 11mm f/4 Firefly is. It opens up a whole new world of creative possibilities in a well-made, well-designed package that delivers the image quality. It will not be for everybody, perhaps because of the ultra-wide style of the images, or maybe because of difficulties using the manual focus system, but if the lens appeals to the individual photographer’s creativity then it will be a rewarding experience.