There are plenty of inexpensive fish-eye lenses out there, including the Lensbaby Circular Fisheye ($228.91 at Amazon) and the Samyang 12mm F2.8 ED AS NC Fish-eye ($524.58 at Amazon) . But there aren't a lot of zoom designs (Pentax and Tokina both sell a 10-17mm fish-eye for APS-C SLRs), and none other that switch from a fully circular field of view to a more traditional fish-eye look as the Canon EF 8-15mm f/4L Fisheye USM ($1,249) can. It also includes autofocus, compatibility with full-frame cameras, and the build quality and weather-sealing that you expect from an L-series lens. The cost may be a turnoff for photographers in the market for what is an occasional-use, special effect lens, but there's no arguing with the quality of the product.

Design
The 8-15mm f/4L Fisheye USM ($1,249.00 at Amazon)  is sized similarly to other ultra-wide zooms. It measures 3.7 by 3.1 inches (HD) and weighs in at 1.2 pounds. The front element is bulbous, and there's no thread to accommodate lens filter use. If you do want to use a filter, you can add up to three pre-cut gel filters to the rear of the lens.

A removable lens hood is included, with a push-on lens cap. I found it easier to leave the cap attached to the hood at all times, and simply remove the hood for shooting. It blocks the full circular field of view when using it with a full-frame camera like the 6D ($1,999.99 at Amazon) , but is easy enough to remove and replace. There's a button on the side of the hoodd to unlock it, and a bayonet mounting ring running along the edge of the front of the lens.

The lens has a single control switch, which is a toggle to change between automatic and manual focus. The zoom ring sits at the base of the lens and includes markings for 8, 10, 12, 14, and 15mm. There are two additional markings—C and H. Turning the notched mark on the zoom ring to either of those will set the lens to its widest field of view where the image covers the entirety of the frame (with no remnants of its circular field of view) on APS-C and APS-H cameras, respectively.

Optics
A manual focus ring sits at the front of the lens, just behind the rear element. The minimum focus distance is 6.2 inches; that's measured from the image sensor, which means that you can put the front element extremely close to a subject and lock focus. If you love distorted portraits with giant noses filling a good portion of the frame, the 8-15mm will make you happy.

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Normally I run Imatest to check a lens for sharpness. With a fish-eye that's difficult, as a standard SFRPlus test chart isn't designed to give proper readings with an extremely distorted frame. I wasn't able to get any meaningful data out of the lens at 8mm, but was able to analyze a portion of the frame when testing it at 15mm.

At f/4, the lens notches an average score of 2,217 lines per picture height at 15mm. That's better than the 1,800 lines we look for in an image. Resolution improves at f/5.6 (2,298 lines) and peaks at f/8 (2,463 lines), before dropping slightly at f/11 (2,357 lines). I'm not going to be as picky with edge numbers (Imatest was not able to analyze those portions of the chart), or even data from the mid-parts of the frame, as the distorted view was certainly fuddling with its numbers. There is some evidence of color fringing in high-contrast areas of the image at 8mm, but it's something that you can remove in Lightroom ($9.99/Month at Adobe) with relative ease.

In the real world, I have no major complaints with how the 8-15mm performs. Details are crisp, even when viewed at full magnification, and the lens is extremely resistant to flare. Even when shooting directly into the sun at 15mm f/8, details in the image below are crisp, and the sun itself shines above the scene with a starburst rendering.

I worked hard to induce some flare around the edge of the lens at 8mm. In one shot I was able to get a little bit of light streaking into the black frame that surrounds it, but I had to make sure the sun was positioned just right, and I had to shoot at f/4 to do so. If you're actually a fan of this effect, check out the Lensbaby Circular Fisheye—you'll have to crop images a bit if you shoot with a full-frame system, and focus manually, but you'll get bright halos around all your shot, a virtue of a lens design that omits an internal baffle that's meant to remove this effect from lenses like the 8-15mm.

Conclusions
As you'd expect with any L lens, the Canon EF 8-15mm f/4L Fisheye USM delivers crisp images, focuses quickly, and is built to withstand the rigors of real-world photography. It's not the only zooming fish-eye on the market, but it's the only one that lets you choose between capturing a full circular image (like the Lensbaby Circular Fisheye) or a more traditional distorted perspective (like Samyang's 12mm prime). Details are crisp, and while I did notice some color fringing in high-contrast areas of the frame when shooting at a wider aperture, those are really only a concern for big prints and pixel peepers, and are easily removed with a few slider adjustments when processing photos. The only real sticking point is the price. $1,249 isn't out of line for a lens of this caliber, but it's a lot to pay for one that is only going to see occasional use. You may be better off carrying a less expensive fish-eye around. I'm a big fan of Lensbaby's inexpensive, manual focus Circular Fisheye lens for that reason—it's tough to beat for its $300 price tag. But if you don't mind spending a bit more, the Canon EF 8-15mm is a fine performer with a unique optical design.

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