# Imaging White Papers

## How To Calculate Total Magnification

# How To Calculate Total Magnification

This article describes how to calculate the effective magnification and the size of your sample on your monitor when using a digital camera on a microscope.

### Magnification on the TV Monitor

In order to determine the total magnification on the TV monitor, the following variables must be known:

- Objective magnification
- Microscope adapter magnification.
- CCD chip diagonal dimension
- TV monitor diagonal dimension

The formula used to calculate total magnification on the TV monitor is:

**Total Magnification =
Objective Magnification x Microscope Adapter Magnification x Video Magnification**

The video magnification is determined by dividing the TV monitor diagonal (mm) by the CCD chip diagonal (mm). A reference chart is given below which shows video magnification for various monitor and chip sizes. To determine "Video Magnification" on a computer monitor divide the actual image diagonal (as measured on the screen) by the CCD chip diagonal.

9" | 12" | 13" | 19" | 20" | 27" | |
---|---|---|---|---|---|---|

1/3" | 38.1x | 50.8x | 55.0x | 80.4x | 84.7x | 114.3x |

1/2" | 28.6x | 38.1x | 41.3x | 60.3x | 63.5x | 85.7x |

2/3" | 20.8x | 27.7x | 30.0x | 43.9x | 46.2x | 62.3x |

1.0" | 14.3x | 19.1x | 20.6x | 30.2x | 31.8x | 42.9x |

What is the magnification on the TV monitor when using a 10X objective, 0.45x video coupler, a 1/2" format CCD and a 19" monitor?

482.6 mm (19"
diagonal) ------------------------------ 8 mm chip diagonal |
||||||
---|---|---|---|---|---|---|

Total Magnification | = | 10 | x | 0.45 | x | |

= | 10 | x | 0.45 | x | 60.3 | |

= | 271.35 |

### Determining the Size of Your Specimen

The approximate real size of a specimen can be determined by dividing the length of the specimen measured on the monitor screen by the total magnification on the monitor.

Length
of Specimen Measured on Monitor Screen ---------------------------------------------------------------------- Total Magnification |
||
---|---|---|

Real Size of Specimen | = | |

In the above example, if the measured length of a specimen was 100 mm, the real size of the specimen would be:

Real Size of Specimen | = | 100 mm / 271.35 |
---|---|---|

= | 0.37 mm |