Canon's full-frame, wideangle-to-fisheye zoom lens attempts to offer more than just a one-trick effect. Mat Gallagher finds out whether this lens really should have a place in your kit bag
A circular fisheye image is a very stylised effect and the lenses that create them rarely conform to regular optical demands. Distortion, for example, is a natural characteristic of a fisheye lens, so to mark a such an optic down for it would be counterproductive. This lens provides extreme barrel distortion throughout the range, and therefore the angle of the camera needs to be carefully observed if attempting a straight horizon. With an APS-C sensor, the distortion effects are less obvious and, at the maximum 15mm focal length, minimal correction is needed.
Aside from the areas of the frame that sit beyond the lens’s image circle, there is little light fall-off, creating a clean, circular fisheye with no sign of vignetting within the limited range on an APS-C sensor.
Our regular image chart was hard to capture with this lens due to the extremely wide view and the distance from the chart required. However, we have captured it at half size in the centre and in the corners of the frame to evaluative edge sharpness as well as maximum performance.
On a full-frame camera at 8mm for a completely circular fisheye, the sharpness appears impressive, resolving to an equivalent of 28 on our chart and remaining sharp right up to the edges of the circle. There is, however, significant signs of blue and magenta colour fringing towards the edges at all apertures. At the 15mm focal length, sharpness remains impressive, with a sweet spot of f/8 for optimum resolution, although edges still suffer from colour fringing. When mounted on the APS-C camera results were similar again, with slightly reduced signs of colour fringing around the edges but good overall sharpness, peaking at f/8.
For comparison, we took the same test-chart shots using the Sigma 8-16mm f/4.5-5.6 DC HSM, a digital-only lens that costs around £550. Designed as a wideangle rather than a fisheye, the Sigma offered a narrower but far less distorted view at 8mm and an almost distortion-free image at 16mm. However, sharpness at f/8 at the centre of the lens is almost identical to the Canon lens.
Image: Napoleon, taken at 15mm on an APS-C sensor
Image: Napoleon, taken at 8mm on an APS-C sensor (cropped to remove vignette)
The animals featured are homed at the Battersea Dogs and Cats Home and they, and many like them, are still looking for new owners. For more information, contact www.battersea.org.uk or 0207 622 3626