https://wiki.henpe.se/ 2026-06-12T02:06:24+00:00 https://wiki.henpe.se/ https://wiki.henpe.se/_media/wiki/favicon.ico text/html 2022-05-25T21:14:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.henpe.se/wiki/phototechniques/focusspread?rev=1653513295&do=diff Equations Basic When a lens is used to form an image of some object, the distance from the object to the lens $u$, the distance from the lens to the image (i.e. film plane) $v$, and the focal length $f$ are related by: \[\frac {1}{f} = \frac{1}{u}+\frac{1}{v}\] which can be rewritten as e.g.: \[v=\frac{uf}{u-f}\] or \[v=\frac{uf}{u-f}\]\[N=\frac{f}{d}\]$d_F$$d_f$$d_r$\[d_F = d_r -d_f\]\[d_f = \frac{uf^2}{f^2 + c^2N(u-f)}\]\[d_r = \frac{uf^2}{f^2 - c^2N(u-f)}\]\[\text{DOF} \approx \frac{2u^{2}…