"As far as I can determine,
bokeh first appeared as a term relating to Western photography in recent history when Mike Johnston introduced it in an 1977 issue of
Photo Techniques magazine."
http://www.imaging-resource.com/new...-and-science-behind-the-beauty-of-blur-part-1. That 1977 seems to be a misprint for the 1997 Mike Johnston himself refers to in a summary of his part in introducing the term to Western photography published by Luminous Landscape:
https://luminous-landscape.com/bokeh-in-pictures/ .
I think the terms "bokeh" (blur) and "bokeh-aji" (the quality of blur) were terms in use in Japanese art criticism before photography. They gave Japanese photographers existing terminology and an interest in that area of photographic image quality and composition. Early lens designs were based on spherical lens elements because aspherical elements were too difficult and expensive to make. Spherical lens elements are not the theoretically ideal image forming shape. They produce a kind of distortion called spherical aberration. They attempted to correct this by introducing converse kinds of distortion to cancel it out. It was observed that the sharpest images with the most corrected spherical aberration introduced an unpleasant character to the out of focus areas. Balancing the image quality of the sharp in focus areas and the blurred out of focus areas was one of the many areas of compromise in lens design which lens makers struggled with, different designers choosing different compromises.
Portrait lenses were an area where photographers were particularly concerned about the quality of the out of focus areas. In the 1990s lens designers started experimenting with special improved bokeh portrait lenses. The outstanding example, still generally recognised as unmatchable in its bokeh, was the Minolta 135mm STF (Smooth Transition Focus), which used an apodization element to fade out the aperture edges, giving blurred highlight circles the look of Gaussian blurred point sources. They say they called it "Smooth Transition Focus" because it's not only the bokeh that's important, but the way the lens handles the transition between in focus and out of focus. The lens, updated for digital camera sensors with improved coatings, is still produced by Sony for its A-mount. A Sony E-mount STF lens is rumoured to be in development.
Like HDR, a lot of ridiculous nonsense is talked about bokeh, and like HDR a lot of bad photos have been produced by over-enthusiastic zealots who photograph everything with the widest aperture and worst spherical aberration they can get their hands on. Like the best HDR, the best bokeh simply improves the image without drawing attention to itself.
I'm grateful to Japanese photographers and lens designers for drawing my attention to this area, giving us the terminology, and designing lenses with which to explore it.
I must admit though my natural instinct Is still to call it "Out Of Focus" area.
