Fstoppers Reviews the Irix 11mm f/4 Firefly Rectilinear Lens

Ultra wide rectilinear lenses are not very common and the few existing options are expensive. But the Irix 11mm f/4 combines non-fisheye design with a friendly price. Is it too good to be true?

Firefly Versus Blackstone Version

Irix offers this lens in two versions for Nikon F, Canon EF, and Pentax K mounts. The regular “Firefly” version and the premium “Blackstone” model. Optically, both lenses share the same design but the Blackstone “has a durable body made with aluminum-magnesium alloy, that ensures foolproof protection of your lens, even in extreme situations” according to the manufacturer. The markings are also engraved and fluorescent which can help during night operation. In my case, I opted for the Firefly version because it’s lighter and cheaper ($525 against $650).

Build Quality, Handling, and Features

The optic comes in an attractive and professional package. It contains a metallic box and the lens is wrapped inside a semi-rigid pouch. This type of packaging is not very common at this price range. Unsurprisingly, for this type of focal, the lens is massive with a huge bulbous front element protected by a fixed lens hood. The width of the lens is almost similar to its length and it can be challenging to fit the Irix in regular camera bags.

In terms of build quality, the Firefly version is well made and nothing feels cheap about it. The focus ring is large with a 150 degrees course (my estimate). A focus lock ring is placed just above the focusing ring which is a nice addition to lock the focus in place but the ring is a bit too narrow for my taste and it can be challenging to properly lock the ring without messing up the focus. But at least, this feature is implemented, which is better than nothing.

The focus is purely manual but the lens is equipped with electronic contacts to enable the communication with the camera body. The aperture is controlled electronically from the camera and the EXIF data is recorded with the picture. Therefore, this lens is compatible with the camera metering and auto-exposure settings.

On the lens, the depth of scale marking is clearly visible and the focus ring has a hard step when the focus ring reaches the infinity. This infinity step is helpful since I mostly used this lens with this setting as it can be challenging to focus precisely with such a wide angle lens even in live view with full magnification. The infinity point was accurate on my copy but the focus can be calibrated via a tiny flathead screw located beneath a cover in front of the lens (you’ll need a T6 Torx screwdriver to open the cover). 

Finally, the lens comes with rear filter slot to accommodate 30x30mm gelatin filters. The cheap ND filters sold by IRIX are completely useless as they tend to wrinkle on first use and are hard to slide in and out of the rear slot. I found that trimming one or two millimeters off of the filter helps the installation process. But most importantly, the strongest ND filter only reaches ND16 level which is not very helpful for long exposure photography. Some users reported buying 50mm filter sheets from a British company called Knight Optical. These industrial filters can be cut and installed in the rear filter slot of the lens. They are available at strong ND levels such as ND1000/OD3, or ND10000/OD4. But be aware that I haven’t tried this solution myself.

How wide Is 11mm?

As a landscape and urban photographer myself, I tend to shoot wide on a regular basis. My go-to lenses for ultra-wide angle photography are the Samyang 14mm f/2.8 and the Canon 16-35mm f/4 but I needed something wider for a particular time-lapse project. Dropping $2,700 for the Canon 11-24mm f/4 lens was not an option and I fell back to the budget friendly Irix Firefly. It’s hard to realize how wide 11mm is on a full frame camera so I compiled a few comparison shots captured with the 11mm Irix, the 14mm Samyang, and the 16mm Canon lenses. The images below are straight out of the camera, shot in raw without any editing or correction. Notice the heavy barrel distortion of the Samyang lens and the color and white balance shift between the lenses.

The Poor Photographer's Tilt-Shift Option

Tilt-shift lenses are great for urban and architectural photography but they are extremely expensive. However, due to the focal of this lens, I used the Irix as a cheap and imperfect alternative for tilt-shift lenses as I was able to straighten the perspective in post-production with the Lightroom Transform tool. The massive field of view allows to frame most subjects even in tight spaces or at close range. The over framing give enough room to play with the perspective tools and crop the image without cutting the main subjects. Of course, this solution can’t replace a proper Tilt-Shift lens but it can help in certain situations.

Here are a few time-lapse sequences shot with the Irix 11mm f/4 and with perspective correction applied in Lightroom.

Image Quality

Traditionally, ultra wide angle lenses don’t break any image quality records as the design of that type of optic is extremely challenging. Keep in mind that all short focal lenses suffer from similar issues but in general, the Irix lens performs well in this class.

Sharpness

This lens is very sharp wide open (f/4) in the center. Surprisingly, the sharpness decreases slightly when stopped down. Overall, the central sharpness is very similar across the aperture range from f/4 to f/9. However, the image quality is already degraded by f/11 due to the diffraction. The resolution curve is more predictable in the image periphery. As expected, the corners are soft wide open but the level of detail improves significantly at f/5.6 and beyond.

Vignetting

The vignetting is pronounced wide open and still visible at f/5.6 but the corner darkness isn’t an issue past f/6.3.

Chromatic Aberration

There is noticeable chromatic aberration in the periphery of the image but fringing and other chromatic issues can be easily corrected in Lightroom with the defringe tool. The lens profile included in Lightroom and ACR also helps to remove that type of issue.

Distortion

The distortion is well controlled but tilting the camera up or down will result in a severe perspective shift as with any ultra wide angle lens. At extreme angles, the image suffers from barrel and mustache distortion but the lens profile embedded in Lightroom does a good job at fixing this issue.

Flare

Flare is always a challenge for ultra wide angle lenses and the Irix also suffers from that type of internal reflection when directly exposed to a strong source of light due to the complexity of the optical design. But the problem can be managed by orienting the camera away from the main light source. In some extreme cases, the flare generates halo in the corners (see the image below) but the situation can easily be corrected my shifting the lens by a few degrees.

Competition and Alternatives

There aren’t many options for rectilinear wide angles lenses. At the widest focal range of 11mm, the Irix lens only competes with the expensive Canon EF 11-24mm f/4L lens ($2,700). Up next is the Laowa 12mm f/2.8 Zero-D ($950) and the Sigma 12-24mm f/4 ($1,600). Finally, the Samyang 14mm f/2.8 has a narrower field of view but comes at $250-$340. In the end, the closest contender against the Irix lens is the Laowa 12mm f/2.8 Zero-D, which offers an additional stop of light to justify to higher price tag. This brighter optic can be appealing for astrophotography but budget-conscious photographers might prefer the Irix if they don’t plan to shoot in complete darkness conditions.

What I Liked

• The only 11mm rectilinear prime lens available on the market for full frame camera
• Excellent value. $525 for a well-built and optically-convincing, ultra-wide angle lens
• Solid build quality, nice focus ring with infinity step
• Good image quality overall in this class of lens
• Very good sharpness in the center even at the widest aperture (f/4)
• Ability to fine-tune the focus ring directly on the lens
• Nice bundle and packaging
• Cheap alternative for tilt-shift style photography

What I Didn't Like

• Strong vignetting at the widest apertures (f/4 to f/5.6)
• Weak corner sharpness between f/4 and f/5
• Unusual sharpness behavior. The central sharpness can slightly decrease when stopped down.
• The focus lock ring is a nice addition, but hard to move and too narrow.
• Poor quality of the rear gelatin filters sold my Irix. The strongest ND filters available are ND16 which is useless for long exposure photography.

Who Is It For?

Urban, real estate, and landscape photographers looking for the widest possible focal without fisheye effect should be pleased by this product. But this Irix Firefly might not be the best choice for astro-photography due to the relative slow aperture (f/4). Astro-photographers might prefer the Laowa 12mm f/2.8 Zero-D ($950) or the Sigma 14mm f1/.8 ($1,600) which is available for Sony E and Leica L mirrorless mounts. Unfortunately, the Irix doesn’t offer this lens for mirror-less cameras at the moment as it can only be fitted on traditional DSLR bodies (Canon EF, Nikon F, Pentax K mounts).

Conclusion: Best Value in Class

The Irix company was created a few years ago and this small manufacturer decided to tackle the market with niche optics. This 11mm f/4 lens made from “Swiss precision and Korean innovation" as Irix says on its website is a well-designed and appealing product in this deserted market segment. To my knowledge, this is the widest rectilinear prime lens available for full frame DSLR cameras. Hopefully, Irix will adapt this lens for new mirrorless mounts in the future. In terms of image quality, I was pleasantly surprised by the optical performance of this glass. The sharpness in the center is very good even at the widest settings, while the corner resolution improves significantly at f/5.6. Vignetting and chromatic aberration are strong at f/4 but they also decrease when stopping down the aperture. To be fair, most ultra-wide angle lenses experience similar issues. But the Irix Firefly is available at $525. Therefore, it is very hard not to recommend this lens if you are looking for an ultra-wide rectilinear optic. The few other options in this class are much pricier and bulkier.