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Irix 15mm f/2.4 Lens Review

Irix 15mm f/2.4 Lens Review - John Riley reviews the new Irix 15mm f/2/4 wide-angle lens for full-frame cameras.

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Irix 15mm f/2.4 in Interchangeable Lenses

Handling and Features
Performance
Verdict
Specification

Irix 15mm F2,4 Blackstone Vertical View

The Irix 15mm f/2.4 lens is an ultra-wide rectilinear manual focus optic for full frame 35mm-format cameras, in this premium Blackstone version also being weather sealed and clad in magnesium alloy. Such a lens is a beautiful object in its own right, but the most important thing is the quality of the images it helps us to make. Let's see if the results are the equal of the outward appearance.

Irix 15mm f/2.4 Handling and Features

Irix 15mm F2,4 Blackstone On Canon 6D

The lens looks the part from the start, impressively mounted on the Canon EOS 6D used for this review. It matches the camera well and balances well. There is no AF, but there are electronic contacts on the mount so the correct aperture is reported in the EXIF data. The aperture, with its nine rounded blades, is controlled by the camera. There is a limitation in that the 6D cannot report an f/2.4 aperture value and instead reports f/2.5. This is a minor point of interest but has no real operational significance.

Mount options are listed as Canon EF, Nikon F and Pentax K, the Canon version weighing in at 685g and the Nikon at 653g. The weight of the Pentax version is not specified. The direction of focusing travel on the sample provided was correct for its Canon mount. Moving from the mount forwards, we find a depth of field scale, very useful when provided.

Next up is the wide manual focus ring, with clear markings in feet and meters. The paint used to fill the high-quality engraving is actually fluorescent, so in dimmer light, the markings stand of especially clearly. An excellent idea. The manual focus ring has more innovation to offer yet. There is a click stop at the infinity position, enabling that point to be found more easily when doing night shoots. There is also a guideline for setting the hyperfocal distance, with markings for f/16, f/11 and f/8. This is another excellent idea.

Forward of the focusing ring we have a focus lock. This enables a point of focus to be locked in and could well be useful when shooting a series of images at a specific distance. It will avoid any inadvertent focus shift. On the underside of the lens, there is also a recess for an adjustment to be made to the focus calibration to match the focusing scale of the lens with an individual camera, if found to be necessary.

Finally, the domed front element is protected by a very wide front rim that accepts not only the bayonet fit lens hood but also 95mm filters. It is very unusual for a lens with an 110-degree diagonal field of view to allow the fitting of filters, but it is possible with this lens. Thin filters will be best, and stacking of filters would almost certainly result in vignetting. If preferred, gelatin filters can be fitted to the rear mount of the lens.

Irix 15mm F2,4 Blackstone With Hood On Canon 6D

The bayonet lens hood deserves a special mention for the small cut out window that enables access to the rim of rotating filters, such as polarisers, to make their use possible when the hood is attached. This has been a hallmark of Pentax lenses for many years, but here the idea is improved as there is a sliding door to gain access rather than a removable panel that can easily be lost.

Lens construction for a 15mm lens has always been complex, even the first 1970s offerings having aspheric elements. This new lens takes that even further, with 15 elements in 11 groups of which we have 3 HR (High Refractive Index), 2 ED (Extra Low Dispersion) and 2 Aspheric elements.

This version reviewed is the Blackstone specification, which is a premium manufacture Aluminium-Magnesium alloy housing with weather sealing. It is beautifully made, with very high-quality finish. There is also a Firefly version available, with a more lightweight plastic construction and a lower price.

Manual focusing with such a wide angle lens can be tricky to judge but was found to be reasonable in practice. Any errors can be covered by the depth of field available, which is quite extensive. However, selective focus effects can be obtained where the main subject is very close to the lens. Arguably the best way to use a 15mm lens is to get in close and make use of the drama of the perspective that the close viewpoint gives. At first, until the feel for the lens becomes second nature, good advice would probably be to get in close and then go closer, which initially goes a little against the grain. The rewards are there to be had, with dramatic, sweeping perspectives.

Irix 15mm F2,4 Blackstone Rear Oblique View
 

Irix 15mm f/2.4 Performance

So, does the technical quality of the lens match its quality feel? 

Central sharpness is excellent from f/2.4 all the way through to f/16. It remains very good at f/22 and makes the inclusion of that very small aperture worthwhile. It means we can usefully take advantage of maximum depth of field when necessary.

The edge results are of course not as good at the close test target distances as they are out in the field. Field curvature makes the shooting of a flat test target more difficult for an ultra-wide lens to shine. As a result, f/2.4 and f/4 are relatively soft at the edges, f/5.6 improves to a good level, but it is not till f/8 that sharpness becomes very good. This becomes excellent by f/11 and remains very good at f/16 and f/22. In any event, this is a much better performance than 15mm lenses tried in the past.


 

 
IRIX 15MM F2 4 MTF
MTF
 

How to read our 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.

For this review, the lens was tested on a Canon EOS 6D using Imatest.

 

Centrally, the CA figures are as close to zero as we could possibly expect, which is outstanding. At the edges, correction is remarkable for such an ultra-wide lens and any residual CA could be easily tackled in software. As it stands, this will probably not be necessary for most shots.


 

 
IRIX 15MM F2 4 CA
CA
 

How to read our charts

Chromatic aberration 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 minimize the problem, hence they usually cost more.

For this review, the lens was tested on a Canon EOS 6D using Imatest.

 

The flare resistance is just about complete and even when shooting right into the light there is no noticeable reduction in contrast. Images remain crisp and there are no spurious artefacts.

Distortion is well held at -2.07% barrelling, which is very reasonable for such a wide lens. Again, for most shots, I would just leave this as it is, although software correction is always possible if required.

The nine-bladed diaphragm, with rounded blades, gives a very pleasant appearance to the bokeh of the lens. It is easily possible to have out of focus areas in even a 15mm lens, especially where the main subject is very close. The gradation of the bokeh is smooth and satisfying to the eye.

So, to answer the opening question, yes, the Irix 15mm f/2.4 Blackstone lives up to its quality feel when the images are examined, and acquits itself very well indeed.


Irix 15mm f/2.4 Sample Photos

Value For Money

The Irix 15mm f/2.4 Blackstone lens is priced at £568. The less expensive Firefly version, with the same optics, is £428.

This compares with the Samyang 14mm f/2.8 ED AS IF UMC at £299. Zeiss also offer a Milvus 15mm f/2.8 at £1999.

Canon users have the EF 14mm f/2.8 L II USM (£1849) and Nikon users have the Nikon 14mm f/2.8 D AF ED (£1389).

For the speed, quality of manufacture and the optical results the Irix lens looks very good value. For more options have a look at the Top 15 Wide-angle Landscape Lenses.

 

Irix 15mm f/2.4 Verdict

The Irix 15mm f/2.4 lens is a powerful photographic tool. This new lens from Irix lifts the performance for such lenses way beyond the first early 1970s offerings and gives us a lens that is free from flare, and very sharp. This Swiss design is an excellent one, built in Korea to very high standards.

Irix 15mm f/2.4 Pros

  • Excellent sharpness, especially centrally
  • No flare evident
  • Virtually no CA
  • Weather resistance
  • Filter use possible
  • Electronic control of aperture
  • Nice bokeh
  • Thoughtful, ergonomic design and features

Irix 15mm f/2.4 Cons

  • Edges soft at wide apertures when close
  • Manual focus only

 

Features4.5/5
Handling4.5/5
Performance4.5/5
Value4.5/5
Overall Verdict

Irix 15mm f/2.4 Specifications

ManufacturerIrix
General
Lens Mounts
  • Nikon F
  • Canon EF
  • Pentax K
Lens
Focal Length15mm
Angle of View110
Max Aperturef/2.4
Min Aperturef/22
Filter Size95mm
StabilisedNo
35mm equivalentNo Data
Internal focusingNo Data
Maximum magnificationNo Data
Focusing
Min Focus28cm
Construction
Blades9
Elements15
Groups11
Box Contents
Box ContentsNo Data
Dimensions
Weight608g
Height100mm

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Comments


derekt 9 United Kingdom
26 Oct 2016 12:42PM
Depth of field is determined by 2 factors: aperture and magnification. i.e. not angle of view or focal length. Same view of caravan above (same size in frame) taken by a 15mm and 50mm will have same DOF. Cutoff to out of focus will be more dramatic with longer lenses, but DOF is about what is in focus not what is out of focus. The effect of the wide angle to give apparent DOF is only due to lower magnification, if you moved in closer it would disappear thus proving it's not a 'feature' of the lens.

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26 Oct 2016 1:51PM
I understand what you're saying derekt and yes, it's all about the aperture and the magnification. However, the practical outcome of this is that when using wide angle lenses in the way that we generally do, we have more depth of field. There are a few areas of photography where what we make use of in a practical way is stated in words that are not strictly accurate, but understood generally as a "rule of thumb" might be. The more we know, the more there is to know.
zeiv 1
11 Nov 2016 3:05PM
I see that you used 6D with Irix 15mm. Many people reported problems with delayed shutter in that combination. Have you had that problem?
I have 5Dmk3 with Firefly 15mm, and I also have problem with delayed shutter (1/2000 acts like 1/10) on all apertures but 2.4.
Also, unable to use off camera flash because of this.
Tried to contact Irix, but no response from them.
11 Nov 2016 4:37PM
I can only tell you that I had no problems using the 6D with the Irex 15mm.
28 Feb 2017 12:14PM
Nice review. Very nice bokeh f-stop series... wish all lens review would contain that Smile
12 Mar 2017 8:08PM
Have used this beauty now for over 3 months on a Nikon D810 and the results are verging on the spectacular, make no mistake this is Zeiss quality for a third of the price.

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