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The visual quality of the out-of-focus areas of a photographic image, especially as rendered by a particular lens.
BY MARK LaFLEUR
One of the most distinguishing characteristics of front anamorphic lenses is the unique out-of-focus areas or “bokeh” they produce. Out-of-focus pinpoint light sources are rendered as elliptical orbs rather than the circular ones produced by spherical lenses. The amount of elongation or squeeze of the out-of-focus areas is directly effected by the squeeze factor of the lens. A 2x anamorphic squeezes the bokeh significantly to create its tall oval shape. In a 1.5x squeeze lens like the P+S Technik 35-70mm T3.2 or the Iscorama adapter we tested, the bokeh is not squeezed as much. It’s squeezed even less with 1.33x anamorphic lenses, and less still with 1.25x squeeze lenses like Panavision Ultra 70. A spherical lens has 0 squeeze factor, so the bokeh remains circular.
The question often comes up: if the image is de-squeezed in post (either by a lens on a film projector or by a post process) and everything else in the frame becomes “normal,” why does the bokeh remain elliptical? The reason is that bokeh, whether it’s out-of-focus areas in the foreground or background of your image takes on the shape of the entrance pupil. The bokeh of your squeezed image isn’t a circular shape that has been squeezed by a factor of 2x, it’s actually an oval shape that has been squeezed by a factor of 2x. If you look through the elements of a spherical lens, you see a perfect circle. If you look through a 2x anamorphic lens you see an oval or elliptical shape. Your subject doesn’t turn into an oval, but the further the distance an object in your frame is from the subject in focus the more they take on the shape of the entrance pupil.
There are companies that make masks for lenses in different shapes including squares and hearts or even your name. When you use these, your subject doesn’t become the shape of the mask, but the out of focus highlights will. This helps illustrate a common misconception about elliptical bokeh. You are de-squeezing the image but the bokeh retains the shape of the entrance pupil, and in the case of anamorphic lenses, the entrance pupil is elliptical.