On a visit to Leica in Solms I spoke with Peter Karbe, head of lens development. He made a point of the fact that Leica lenses are designed to produce their very best performance even when used wide open and he encouraged the use of the lenses without stopping down. It is referred to as “the Leica look”. But what happens in areas of the image that are not sharp? The Japanese have coined the term “bokeh” defined as “the way the lens renders out-of-focus points of light”.
Those areas outside the depth-of-focus represent a creative tool that makes for unique images. The effect produced can isolate the subject from the background and foreground dramatically. The bokeh varies with the f/stop used, by the number of blades in the diaphragm and by the focal length of the lens. There is also quite a bit of variation among different lens brands and the bokeh of Leica lenses is legendary.
I enjoy the images produced by the 50mm Summilux-M lens at widest aperture and especially at the minimum focusing distance. When I approach a subject that lends itself to this technique, I set the diaphragm at f/1.4 and the focus at one meter and just move closer until the rangefinder images come together on my chosen plane of focus. The photos in this post illustrate this effect with subjects at various distances from the lens, but mostly close in. Using the lens wide open calls for careful focusing and the closer you get to the subject, the more critical it becomes, but you do have the advantage of high shutter speeds.
You can see more images captured with this technique in the album “Song of the Summilux” on Carl’s profile on Facebook.