Wide-angle lenses are more susceptible than most to chromatic aberration, that blue/purple or green fringing you sometimes see in photos and videos. To date, we've seen coatings designed to combat it and software processing to compensate for it. Canon's taken a new approach, dubbed BR optics (Blue Spectrum Refractive) which debuts in the long-awaited replacement for its 35mm f1.4L pro lens.
Aberration occurs because light waves hit the focal plane -- in this case, the sensor -- at different points because of the difference in wavelengths. When the light doesn't converge precisely to a single point on the sensor, you get those annoying colored halos. Canon has created an optical element with a center comprised of organic material that best refracts blue wavelengths to improve the convergence properties of the lens.
Here's how Canon illustrates it:
Canon claims this technology "completely corrects" chromatic aberration, and works better than fluorite coatings and and Super-UD (ultra low-dispersion) glass.
The lens looks similar to the old model and takes the same 72mm filters, though it's slightly longer to accommodate three more lens elements, which Canon says improve image quality as well. Other enhancements include modern coatings like Canon's Sub-Wavelength Structure Coating, an inch/25mm shaved off the minimum focus distance and a slight increase of its maximum magnification to .21x up from .18x.
The EF 35mm f1.4L USM II is expected to be available in October for $1,800 (which directly converts to £1.165 and AU$2,530, a lot more than the $1,480 (£990, AU$1,900) of the current lens.