function depthOfField
lens.ts:376
The sharp band around the focus distance.
Written in millimeters throughout and converted once at the end, because the focal length is the smallest term in every one of these expressions and mixing units is how a depth-of-field formula silently becomes a scale factor. A lens focused at infinity is the limiting case rather than a special one: its near limit is the hyperfocal distance.
ReturnsDepthOfField