DOF
& Hyperfocal Distance
by J. Ramón Palacios
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|
The
Formulas
You
may want to understand the relationship of the variables or make
your own computations, so below you can find the equations.
|
Focusing
at the hyperfocal distance. Nikon F5, Nikkor 17-35mm f/2.8D
ED IF AF-S.
2nd Nikonians Photo Adventure Trip. Sand Dunes, Monument
Valley, AZ
|
Hyperfocal
Distance
As mentioned before, setting focus at H, the Hyperfocal Distance,
gives maximum depth of field from H/2 to infinity.
H
= (L x L) / (f x d)
Where:
|
H |
= |
Hyperfocal Distance (in millimeters) |
| L
|
= |
Lens
focal length (i.e. 24mm, 28mm, 35mm, 45mm) |
| f
|
= |
Lens
aperture f-stop |
| d
|
= |
diameter of circle of confusion (in millimeters) |
|
|
| i.e. |
for
DX digital format d |
= |
0.020 |
|
|
for 35mm film format d |
= |
0.025 |
|
for 6x6cm film format d |
= |
0.045 |
|
for 4x5in film format d |
= |
0.1 |
|
NEAR
FOCUS LIMIT
This is the distance from where acceptable
focus starts, when you focus at a given distance, whether that
distance is the Hyperfocal or not.
NF
= (H x D) / (H + (D - L))
Where:
|
NF |
= |
Near Focus Limit (millimeters) |
| H |
= |
Hyperfocal Distance (in millimeters, from above equation)
|
| D |
= |
Distance
at which the lens is focused |
| L |
= |
lens focal length (i.e. 24mm, 28mm, 35mm, 45) |
FAR
FOCUS LIMIT
This is the distance where acceptable
focus ends, when you focus at a given distance, whether that distance
is the Hyperfocal or not.
FF
= (H x D) / (H - (D - L))
Where:
| FF |
= |
Far
Focus Limit (millimeters) |
| H |
= |
Hyperfocal Distance (in millimeters, from above equation)
|
| D |
= |
Distance
at which the lens is focused |
| L |
= |
lens focal length (i.e. 24mm, 28mm, 35mm, 45) |
DEPTH
OF FIELD
The distance between the farthest
and nearest points which are in focus
DOF
= FF - NF
Where:
| FF |
= |
Far
Focus Limit (millimeters) |
| NF |
= |
Near Focus Limit (millimeters) |
Notes:
- Circle of Confusion diameters used here are based on acceptable
sharpness
while viewing an 8x10 inch print at arms length.
- Multiply inches by 25.4 to convert to millimeters.
- Divide millimeters by 25.4 to convert to inches.
- True f-stop value of apertures was used in the calculator as
per this table:
-
| f/1 |
f/1.4 |
f/2 |
f/2.8 |
f/4 |
f/5.6 |
f/8 |
f/11 |
f/16 |
f/22 |
f/32 |
| 1.0000 |
1.4142 |
2.0000 |
2.8284 |
4.0000 |
5.6568 |
8.0000 |
11.3137 |
16.0000 |
22.6274 |
32.0000 |
|
