Dodgy zdepth to defocus expression

gistfile1.tcl

set cut_paste_input [stack 0]
version 8.0 v6
push $cut_paste_input
Group {
name ZDeefucoos_Depth_to_Direct
help "So confuse?\nThis transforms your depth (in meters) into a beautiful defocus map that can be used with the direct mode in Zdefocus and such.\nThe value of the circle of confusion is sensor dependent but seems to always be somewhat around 0.025."
tile_color 0xff5e00ff
label "of Doom"
selected true
xpos 6248
ypos 9152
addUserKnob {20 User}
addUserKnob {7 focusDistance l "Focus Distance"}
focusDistance {{curve R k x1014 27 s9.999999747e-05 t-1 v1.573653698 x1028 3.3 s0 x1052 5 s0}}
addUserKnob {41 f l "Focal Length" T MergeExpression2.f}
addUserKnob {41 N l f-Number T MergeExpression2.N}
addUserKnob {41 c l "Circle of Confusion" T MergeExpression2.c}
}
Constant {
inputs 0
color {{parent.focusDistance}}
name Constant4
xpos 440
ypos 345
}
Input {
inputs 0
name Depth
xpos 561
ypos 86
}
Clamp {
minimum_enable false
maximum {{parent.MergeExpression2.h}}
name Clamp2
selected true
xpos 561
ypos 272
}
MergeExpression {
inputs 2
temp_name0 s
temp_expr0 Ar
temp_name1 bl
temp_expr1 abs((f/N)*((Br-s)/(s+abs(Br-s))))
temp_name2 blur
temp_expr2 "isnan(bl)?1:bl "
expr0 blur
expr1 blur
expr2 blur
expr3 blur
name MergeExpression2
xpos 561
ypos 368
addUserKnob {20 User}
addUserKnob {7 f l "Focal Length"}
f 40
addUserKnob {7 N l f-Number}
N 4
addUserKnob {7 c l "Circle of Confusion"}
c 0.025
addUserKnob {7 h l Hyperfocal}
h {{pow(f,2)/(N*c)}}
}
Output {
name Output1
xpos 561
ypos 468
}
end_group