Monthly Archives: June 2019
The number and shape of aperture blades
The arrangement of the lens aperture affects not so much the quality of the blur as the shape of the blur circles. In fact, so-called blurring circles rarely have a perfectly round shape. They usually look like more or less regular polygons with the number of sides corresponding to the number of diaphragm lobes. The aperture in Nikon lenses has 7 or 9 lobes, in Canon lenses – 6, 7 or 8 (occasionally 9). The more petals there are, the more rounded the blurring disk looks, and an odd number of petals usually produces polygons that are more pleasing to the eye. Continue reading
Bokeh (English. bokeh; YAP. 暈け or ボケ – “blurring”) is a characteristic of the aesthetic qualities of the image area that lies out of focus, i.e. outside the grip area. Bokeh has nothing to do with sharpness: two lenses that depict objects in focus equally sharply can have a completely different blur pattern, the subjective artistic merits of which are described by the term bokeh.
An ideal lens from an engineering point of view focuses light from a point source in the form of a regular cone. When the tip of the cone touches the plane of the matrix or the camera film, the image is in focus and the photo gets an extremely small point. Continue reading