## Depth of Field Equations

http://www.dofmaster.com/equations.html

Hyperfocal distance, near distance of acceptable sharpness, and far distance of acceptable sharpness are calculated using the following equations*:

Hyperfocal distance:

Near distance of acceptable sharpness:

Far distance of acceptable sharpness:

where: | |

H |
is the hyperfocal distance, mm |

f |
is the lens focal length, mm |

s |
is the focus distance |

D_{n} |
is the near distance for acceptable sharpness |

D_{f} |
is the far distance for acceptable sharpness |

N |
is the f-number |

c |
is the circle of confusion, mm |

f-number is calculated by the definition *N = 2 ^{i/2} , *where

*i = 1, 2, 3,…*for

*f/1.4, f/2, f/2.8,…*

Calculations using these equations must use consistent units. When focal length and circle of confusion have units of millimeters, the calculated hyperfocal distance will have units of millimeters. To convert to feet, divide *H* by 304.8. To convert to meters, divide *H* by 1000.

An online calculator of DoF

An DoF calculation example: Canon T3i(1.6x CF), Canon 50mm F1.8 lens, Object distance 0.45m, a very shallow 0.49 cm DoF is produced by the lens.

Subject distance | 45 cm |

Depth of field | |

Near limit | 44.8 cm |

Far limit | 45.2 cm |

Total | 0.49 cm |

In front of subject | 0.24 cm (50%) |

Behind subject | 0.25 cm (50%) |

Hyperfocal distance | 7389.6 cm |

Circle of confusion | 0.019 mm |

==================================

*Greenleaf, Allen R., *Photographic Optics*, The MacMillan Company, New York, 1950, pp. 25-27

## 2012 Great New England Airshow

Great New England Airshow in Westover ARB. Drove 100 miles to the air base and GREAT FUN!

Canon 55-250mm lens is cheap but really worth the price!

1. Low pass with gear up

2. Super sonic flyover

3. P51 Mustang, fastest propeller in WWII

4. C-130 Hercules is taking off.

5. C-130

6. F-15 low pass

7. F-15