The Sigma 4.5mm circular fisheye lens for APS-C sized digital SLRs is a fascinating lens.
180 degree circular fisheye lenses are very unusual. For the photographer they can be a challenge to use well, though they reward the effort with a very different view of the world. For the lens designer they are also a challenge to produce with good image quality at a reasonable price.
Sigma’s new 4.5mm F2.4 circular fisheye lens fits Sigma, Nikon and Canon digital cameras that have an APS-C sized sensor. So it basically works with all their digital SLRs except those with full-frame sensors. We tested the lens in a Canon mount. The lens is neither large nor small, having dimensions of 76.2mm diameter and a length of 77.8mm (3.0 inch and 3.1 inch respectively). At 470g or 16.6oz it is a reassuring weight that speaks of quality construction. And that it has. The finish of the lens is excellent, as is its operation.
Put the lens on a camera and the world starts looking very weird. It has a 180-degree field of view, which makes it very easy to get your feet (or in my case stomach) in the shot if you are not mindful. It focuses down to 13.5cm or 5.3 inches, giving a 1:6 magnification. A lens like this takes some getting used to. But once you do, you find it hard to let go of. It has huge potential from closeup to landscape and more.
Apertures range from f2.8 to f22. Both extremes are quite soft, with apertures of f4 and f16 being noticeably sharper. The sharpest aperture is f8, though f5.6 and f11 are very close indeed. The lens is quick to focus and I experienced no focus issues with the 350D, 400D or 40D that I tested it on. Right at the edge of the image the sharpness falls off and the aberrations kick in, but the performance really is amazingly good.
Exposure can be tough, not because of any issue with the lens, but just because of the huge field of view. After a lot of experimenting I settled on shooting a three frame bracket with one stop over and under. This not only gives you the option of HDR but also, I found, guarantees you a good compromise exposure in at least one of them.
The close focusing ability can come in handy
One trap to avoid is the lenscap: it is in two parts. I missed this the first time shooting and only realized when examining the images later. There is a normal lenscap but this attaches to what looks like a lens shade whose purpose is to keep the lenscap off the front element of the lens.
This is a brilliant lens. It will not be everyone’s cup of tea, though. It is a specialist lens that requires effort to come to grips with. I loved it and was very sad to give it back.
You can see how it performs in infrared in the following articles:
The Sigma 4.5mm has a list price of US$1,400.