South & Southeast Asia
South & Southeast Asia
One key objective of Canon’s lens development efforts is to achieve superior optical performance when rendering out-of-focus areas of the image, as well as the parts that are in focus. This is particularly important when trying to take pictures with a bokeh (unfocused background) effect; the overall quality of the photo will depend on how effectively it depicts the out-of-focus areas. Bokeh is a photographic effect that conveys a very strong impression; it is one of the most important features of large-diameter lenses with wide apertures. In general, as the optical performance of a lens improves, the outlines of all portions of the image become clearer, even those that are out of focus. This result is not necessarily a positive one, in all situations. Sometimes, the sharper outlines can interfere with the bokeh effect in a way that makes the subject too emphatic. Canon realized that photographers prefer to have other options, in terms of how sharply each part of the image is rendered, when trying to create the bokeh effect.
Efforts to address this issue culminated in Canon’s proprietary Defocus Smoothing (DS) coating, a vapor-deposition film technology. The base lens design that adopted this coating was the RF85mm f/1.2 L USM, an ideal portrait lens and a symbol of Canon’s optical technology. While maintaining its high resolution, high contrast, and suppression of chromatic aberration, this lens is capable of producing a unique bokeh effect that softens the outlines of a blurred subject. The coating gradually reduces light transmittance (light is blocked) from the center of the lens to the periphery, limiting the amount of light that passes through. The result is a lens that can produce bokeh images with soft, smooth contours.
For the RF85mm f/1.2 L USM DS, a DS coating was applied to the surface of the, in order to maximize the effect. The resolution of the in-focus areas of a subject is very high, while the contours are softly blurred. The lens can be used with a maximum aperture setting of f/1.2, further enhancing the range of expression possible in portrait photography.
