Irix 11mm f/4: Thorough Test and Impressions from Alberto Bouzón

[Translated from blog.foto24.com]

Almost a year ago I acquired my first lens from Irix, the 15mm, and every day I am more delighted to have done so. When I found out that an Irix 11mm f/4 had come out, and considering the maximum quality of the 15mm, I did not hesitate to buy it. Now that a few months have passed and I have tried it in my day to day photography, I could not be more satisfied with this jewel of the Swiss brand, and I enjoy every time I go out with it on my camera.

Irix is ​​a brand that is here to stay...

Introduction

When I wrote about the Irix 15mm model, I told you a little about the history of this new brand that had just emerged on the international photographic scene. Today, I can tell you that this Swiss manufacturer is entrenched in the market and has also shown its solvency, giving total satisfaction, constantly developing new products such as its Edge Filters.

All of this means that Irix is ​​a brand that is here to stay in the photographic market with products of the highest quality at very reasonable prices and well-guaranteed through its distributors.

So, when I saw the first announcements and test pictures of this lens, I was surprised by the impressive angle of view it offered and especially the almost total absence of geometric distortion for such an ultra wide-angle lens. I was amazed.

I want to take the opportunity to explain to those photographers who are beginning in the world of photography that it is important to differentiate between the geometric distortion that makes straight lines look like curves in our photos and distortions of perspective that arise by tilting the camera with respect to the plane of framing, producing the typical convergence of lines. The first are a defect of the optics, from poor design, or at least not very successful, and the second are laws of optics that can only be solved with tilt/shift lenses or with specialized cameras.

Having explained that, I must say that in the photos produced by the Irix 11mm straight lines appear completely straight. Only in vertical lines near the right and left edges can you see minimal curvature as shown in the distortion diagram. In practice, I can say that this distortion is barely noticeable.

By downloading and applying the Lightroom and Adobe Camera Raw lens correction profiles directly from the Irix website, the slight distortion is corrected instantaneously. The convergence of lines is another story and is corrected easily by framing correctly or with the corresponding software.

Why an Ultra Wide-Angle Lens?

When I decided to buy the Irix 11mm, the question arose whether the field of view of 11mm and 15mm would be very similar and overlap.The answer is no. Although there are only four millimeters of difference, in the wide angles those few millimeters of focal length amount to a world in terms of angle of framing.

In fact, this had already happened when I added the 15mm to my backpack, since I already had a 20mm from another manufacturer. The difference between the two was also immense in terms of the amount of landscape that "fit into" the photo.

First, we need to differentiate between the use of the lens on full frame (EF in Canon or FX in Nikon, etc.) or in cameras with crop sensors (EF-S in Canon or DX in Nikon, etc.)

This is an ultra-wide-angle lens that will be used primarily for landscapes and architecture.

On cameras with APS-C crop sensors, having an approximate factor of 1.5X, this lens will be equivalent to about 16mm, which makes it a great option for crop-sensor photographers who want a wide-angle lens. In addition, these cameras will capture only the inner part of the image circle. This means that the quality will be the best possible and you'll obtain magnificent images with incredible definition, super-sharp and with minimal chromatic aberration. (We'll discuss these characteristics further, because chromatic aberrations are actually minimal throughout the whole lens, whether shooting with APS-C or FF.)

On full-frame cameras the use of an 11mm allows you an incredible field of view, ideal not only for landscapes, but also in architecture since it allows you to capture such a surprising amount of detail in the photo. As mentioned before, your photos will show hardly any deformations. The full-frame sensor takes full advantage of the image circle, even at the edges, but thanks to the superb quality, we will have incredible resolution without loss of sharpness, as well as minimal vignetting, etc.

Another field where this lens offers applications is sports photography or videography, since the wide field of view allows you to capture, for instance, all of a skaters' moves, all the jumps of the athletes and the complete descents of bikers, more mountaineers, etc.

Despite the spectacular width of the shot, however, this lens is not at all "radical", that is, it is not the typical fisheye that creates striking but really unusable images. The images produced by the Irix 11m are always elegant in the straightness of their lines, making them more interesting from an artistic point of view than the jarring distortion of fisheyes.

A Wide Maximum Aperture: f/4

To some, that statement will seem strange, because f/4 is not usually considered a wide aperture, when compared to lenses with maximums of f/1.4 or f/1.2. However, we are talking about an 11mm lens with complex optical construction, not a 50mm. Also, because of the type of photographs we will be taking, we will be more interested in narrower aperture settings than wide ones.

This is an ultra-wide-angle lens that will be used primarily for landscapes and architecture. We will almost certainly need maximum depth of field to bring everything into focus in our images. In 90% of our shots we will probably use intermediate aperture settings from f/8 to f/16.

We will also look for maximum definition and sharpness so we will surely take our photos with a tripod, with mirror lock and even with remote shutter, so we can use relatively low shutter speeds.

Even without a tripod, using an 11mm lens, we will be able to take pictures at a fairly low speeds of around 1/10s or 1/15s with almost no worry.

Besides, with the quality of today's camera sensors, we can raise the ISO setting and not lose practically no definition, with noise very well controlled.

Use of the Irix 11mm f/4 in Night and Star Photography

For this type of photography it might seem that the use of an aperture of f/4 could be a disadvantage, since increasing the exposure time will eventually cause the stars to record as streaks rather than sharp pinpoints. However, with such a wide a short focal length, applying the well-known 500 rule will show that we can increase the exposure time considerably and still successfully capture a sky full of stars.

...using the Irix 11mm will allow you to lower the ISO further, resulting in an image with less noise.

Let's look at an example: I have in my backpack the Canon EF 24-70 f/2.8 L and the Irix 11mm. Let's assume that they are optically similar, although we already know that fixed (prime) lenses are generally sharper than zooms.

Let's take a picture of the night sky with both lenses with the same camera, in my case with the Canon 6D.

With the 24-70 at 24mm and F2.8 applying the rule of 500 would give us an exposure time of 500/24 = about 20 seconds, then complete the exposure calculation with the corresponding ISO.

With the Irix 11mm to F4 and again applying the law of 500 would give us an exposure time of 500/11 = 45 seconds, then complete the exposure calculation with the corresponding ISO setting.

The difference between an aperture setting of f/2.8 and f/4 is a complete stop, but factoring in the exposure times above, the difference is greater than one full stop. This means that in this situation, using the Irix 11mm will allow you to lower the ISO further, resulting in an image with less noise.

That's not the end of the story, however, because with the incredible angle of view, I can include heaven, earth, sea and everything I need without having to shoot multiple frames. If you want to know how to take photographs of the Milky Way, you can not miss this post.

In addition, shooting at f/4 and focusing at the hyperfocal distance for that aperture (which is also marked on the lens barrel) will allow me to have a higher percentage of the shot focused than using an f/2.8 lens with a larger aperture. This will allow me to assure that not only the sky is in focus, but also the "terrestrial landscape".

Construction Quality

I've shown the reasons to buy an ultrawide-angle, Irix 11mm, although it is "only" f/4, and why it is a very viable option. Now let's focus on the other aspects that make this lens magnificent. In this section we will focus on the quality of construction.

As you already know, there are two versions of the lens, the Blackstone and the Firefly. To see the differences between the two, you can simply refer to this table, since the lenses are optically identical:

Lens Version

Firefly

Blackstone

Housing material

Lightweight material, 12% weight saving

aluminum-magnesium alloy, premium finish

Housing Outer Finish

standard

anti-scratch

Focus ring material

anti slip coating

all-metal anodized ring with grooved surface

Markings

printed

engraved

Markings Paint

standard

UV light reactive paint

Weather

sealing

front lens element

no

focus lock ring

yes

focus ring

yes

camera mount

yes

Protective case included

soft lens pouch

hard lens case

Which lens you choose will depend on how you use it and the environments you use it in. If your use will be conventional and sporadic as an amateur photographer I recommend the Firefly version for price and weight. If you are a professional photographer and you are going to be an intensive user, I recommend the Blackstone version. In either case, the price is much lower than other lenses with similar characteristics (not that there are many options but there are very expensive).

I have the Blackstone model and the finish is magnificent, similar to the Irix 15mm but with the lens hood integrated and non-removable. This shade is much more resilient than its 15mm counterpart since it is fixed on the lens and can not be removed.

Apart from the sealed elements reflected in the previous table, the materials used in the Irix 11mm are magnificent. The feeling of solidity is great and more so when you have it in your hands. Although it is not extremely heavy, you'll feel the solidity of it.

The metallic focusing ring of the Blackstone is a plus, although the rubber grip of the Firefly is not going to lag behind, because it has a nice feel that provides as much confidence as metallic.

In short, the quality of the lens is superb and hardly surpassed by other brands.

Simplicity of Use

If using the 15mm was simple, using the Irix 11mm is even more so, especially since it has the hyperfocal scale engraved on the focus ring for the apertures of F4, F8, F11 and F16. Even at maximum aperture, you can align the 4 on the hyperfocal scale with the focus mark and know that everything is in focus from infinity to slightly less than two meters away. In other words, practically everything is in focus except the very closest objects.

If you want to focus on a particular element to get the highest level of sharpness, you only need to center the object on the active focus point and gently turning the focus ring until it lights up in the focusing screen and the characteristic focus confirmation beep sounds. It's as simple as that.

For night photography, to achieve the maximum level of focus on the stars is as simple as turning the focus ring until you pass over infinity, even in the dark and totally blind. You will notice a small click that tells you that you are focused at infinity.

It is difficult, if not impossible to not to use this lens well, even more so than the Irix 15mm!

To learn or review how to use hyperfocal distance and manual focusing, please see this article.

The optical quality of the lens is magnificent...

Image Quality

The optical quality of the lens is magnificent and I state that from the perspective of having compared it with other prestigious lenses I have had the opportunity to use.

It stands out for three key aspects just as the Irix 15mm: sharpness and resolution, minimization of Chromatic Aberration and the absence of geometric deformations horizontally as well as near-absence vertically, as previously mentioned. Let's analyze these characteristics one by one and as well as other important considerations.

Sharpness and Resolution Capacity

The sharpness of the Irix 11mm is surprising, although it is noticeable (as in almost all lenses) that the center it is somewhat sharper than the corners.

Here are the MTF curves for the lens:

I n simple terms, the resolution is around 100 percent horizontally at the center and drops only slightly at the corners on a full frame. Vertically, it remains constant between 100% and 90% and only begins to fall near the corner for APS-C, in a very smooth progression.

In the curves at 30 lp/mm which refers to the maximum resolution, we see that horizontally it remains above 85% and only falls when almost at the corner. Vertically, due to the slight distortion of the ultrawide-angle the curve is more difficult to maintain, but it is still good.

So, in terms of sharpness this lens is excellent in both the horizontal and vertical planes and resolution is excellent in the horizontal and good in the vertical. Believe me when I say that few lenses perform this well and even fewer in the case of wide-angle lenses. Search the internet for the curves of other wide-angle lenses and compare them to the Irix 11mm.

In practice, and as you can see in all the images in this article, the sharpness is very good even at the edges. Consider that with this lens you almost photograph your feet when you are taking a picture on the horizontal plane. This not a standard lens of 35mm or 50mm focal length.

In this photo, for example, you will notice the excellent overall sharpness. The details are very well defined from corner to corner.

In looking at the two outlined crops on the left, zoomed to 100% you will observe plenty of detail both in the lower left corner and in the left central area.

The final proof is to read the manifesto of the City of Cañaveral de León you can see hanging on the wall of the town hall.

What did you expect, to read it the whole text? That's too much to expect from the lens or the camera. However, you'll notice that the line "Important Notice" is legible, despite the extreme enlargement of the image. I think this serves as a good example of resolving capacity of the Irix 11mm.

Chromatic Aberration

Like its 15mm brother, another of the aspects in which this lens stands out is that it does not produce chromatic aberrations even in the most complicated conditions. Although with the right software these aberrations can be corrected fairly well today, it is stll a problem. It is better not to have to correct these aberrations since I will have more detail and resolution in the image, I will get more fidelity of color and above all I will not have to waste time correcting it. No matter how good I am, it will not be the same as not having them from the beginning.

In this sunset we can see the "fringes of the umbrella" which are just a few strands. Because of the corner position and because of backlighting, most lenses would generate some colored fringing that we know as chromatic aberrations. The magenta and green edges are surprisingly nonexistent for this type of shot:

I could provide more examples, but instead, take a look at the previous photo of the pool of the Plaza del Agua in Cañaveral de León and notice the crop of the upper area. There you will notice that the branches do not present any type of chromatic aberration.

Geometric Distortion

We have already talked long and hard about the scarce and almost nonexistence of geometric distortion. At the beginning of the article I included a diagram that demonstrates that only in some vertical lines there is a slight curvature. The truth is that this seems magical, because other wide-angle lenses of proven quality always produce curvatures in the lines. Although there are profiles for correction or programs for distortion reduction and/or correction we will always have some cropping of the image, losing some of the angle of view. This defeats the purpose of shooting with an ultrawide lens.

This aspect of the Irix 11mm may seem magical, but it is not magic. It is the good work of the Swiss optical engineers who have designed an exceptional lens.

I'm not going to add any example pictures at the moment because I'm going to analyze the vignetting and then, with a single image I'll convince you of the magnificent work Irix has done with this lens.

It is almost impossible for a lens with this field of view not to produce a bit of vignetting.

Vignetting

It is almost impossible for a lens with this field of view not to produce a bit of vignetting. The optical construction that allows me to "fit" such a wide field of view on the sensor has that drawback. However, it is minimal if we compare the Irix 11mm with other wide angle lenses.

I now show you a photograph that serves to document both the control of geometric distortion and vignetting.

This photograph is taken deliberately in vertical format so that we can see a slight curvature at the ends of the eaves of the church of San Pedro. Also, if we look closely at the first row of granite blocks on the ground, the curvature is slight but it is there.

Look also at the lines that make up both the portico and the door itself, in this case vertically where no distortion is visible. Even in the vanishing lines that make up the floor tiles, no distortion is visible. It is clear that I have to straighten the shot, but first I have to straighten my eyes and my brain, and I have been trying for years and haven't accomplished that.

...they have also been able to complement it with lens correction profiles for both Lightroom and ACR that allow correcting those minimal inconveniences.

You can also see that there is a bit of darkening in the corners due to the slight vignetting that this lens exhibits. As you can see, distortion and vignetting are almost nonexistent.

The Irix engineers have not only done a good job optically with their lenses; they have also been able to complement it with lens correction profiles for both Lightroom and ACR that allow correcting those minimal inconveniences. So after applying these profiles in LR, the shot is perfect... well at least "technically" because the "artistic" part is up to the photographer.

Coma Effect

I have already mentioned that, from a practical point of view, I see very interesting possibilities for the use of this Irix 11mm lens for night photography. That point becomes even stronger if we take into account that it hardly presents the so-called Coma Effect.

The "coma effect" is very simple and I can explain it in a heartbeat. When we photograph a starry sky with some lenses, especially wide angles, some points appear to have "tails", like the coma of a comet. This is due to the distortion of points of light located away from the optical center of the lens, causing them to appear to have protrusions.

Despite being an ultra-wide-angle lens,the Irix 11mm exhibits very little coma effect...

This aberration is usually more likely to appear in the corners of the frame. All lenses present these effects to some degree. Despite being an ultra-wide-angle lens,the Irix 11mm exhibits very little coma effect, rendering the stars nicely as points of light.

Flares and Sparkles

For all wide angle lenses, flare and "sparkles" are difficult to avoid, since having such a wide field of view angle makes it very easy for unwanted light to enter our shots. However, Irix engineers have done an extraordinary job in containing these optical phenomena despite the extreme wide angle of view.

For example, in daylight photos with direct sunlight, the appearance of flares is barely noticeable:

Only with the sun directly on the lens have I managed to capture some more obvious flares, but the moment I change the framing a bit, the flare disappears:

If the photo is taken at night and we have high-intensity lights, we will have to make a little more effort to avoid too much sidelight, but even so, flares are minimal.

Using Irix Edge Gel ND filters

We have explored the advantages of using Irix gel filters in previous articles. These filters are perfectly suited to the Irix 11mm, since it has no fron filter thread and no filter holder is available. Through the use of Irix Edge gel filters in the rear slot, we solve this problem with minimal expense and obtain great results.

For example in the photo above, taken under the pier of the Club Nautico del Nuevo Portil, I used the Irix 11mm with two ND4 gel filters, reducing the light input by four stops. This allowed me to shoot at a shutter speed longer than 1-1/2 seconds, creating that velvety effect on the Piedras River and emphasizing a little more the movement in the clouds.

In short, this is a magnificent ultra wide-angle lens at a surprisingly reasonable price...

Conclusions

Ultimately, the Irix 11mm lens is a surprising achievement, since it is an ultra wide-angle with minimal barrel distortion, with everything that entails. It has enviable definition and sharpness. With its unique system of use and handling, the fact that it is a manual focus lens does not produce any inconvenience. Using it is extremely fast; in fact, using the hyperfocal scale to focus for the aperture used is almost instantaneous and ensures maximum depth of field.

In addition, consider all the other features that make the Irix 11mm a great investment:

• Rear filter slot
• Focus lock
• Focus calibration access (which by the way I never had to use)
• Much more

In short, this is a magnificent ultra wide-angle lens at a surprisingly reasonable price of half the cost or less of comparable quality lenses.