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--- wiki:phototechniques:focusspread [2022/05/24 21:04] – created henpe
+++ wiki:phototechniques:focusspread [2022/05/25 23:14] (current) – henpe
@@ Line 1: / Line 1: @@
-====== Focus Spread ======
+====== 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
+\[v=\frac{uf}{u-f}\]
+Jada jada...
+\[N=\frac{f}{d}\]
+===== Circle of Confusion =====
+==== Standard ====
+^ Format    ^ CoC  ^ CoC ^
+| 6 x 4.5   |      |     |
+| 6 x 7     |      |     |
+| 4" x 5"   |      |     |
+===== Depth of Field =====
+The depth of field $d_F$ is simply the relative distance between the front and rear limits $d_f$ and $d_r$ respectively:
+\[d_F = d_r -d_f\]
+\[d_f = \frac{uf^2}{f^2 + c^2N(u-f)}\]
+\[d_r = \frac{uf^2}{f^2 - c^2N(u-f)}\]