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How to Calculate the Magnification of a Microscope?

01 January 2022

A microscope is an instrument mainly used to magnify tiny objects for the human eye to see. Optical microscopes can magnify objects upto 3000x (generally is 1000x), and the minimum resolution limit is 0.1 microns.

You need to know the power of the eyepieces and objectives to determine how much magnification your microscope can magnify. The magnification of the eyepiece, you can find it marked on the outside of the eyepiece, which usually magnifies 10x. Next, look for the magnification capacity of your objective lens. You can find this on the side of the lens. Traditionally the value can vary among 4x, 10x, 40x, 100x. The magnification is the eyepiece magnification multiplied by the objective lens magnification: 40x-1000x.

Total Magnification = Eyepiece Magnification X Objective Magnification

A common question when viewing microscope images on a screen is: What is the total magnification viewed on the monitor? “In order to correctly calculate the total video monitor magnification, you need to know the following values:

Objective Magnification (Pic.1)

If you are using a stereo microscope the objective lens value would be printed on the zoom knob or on the objective turret that is turned to change the microscope magnification.                                                                                                 


Video Adapter (Microscope Adapter/ C-mount Adapter/ Reduction Lens/ Relay Lens) (Table 1 and Pic.2)

Monitor Ratio: Monitor ratio according to monitor size and sensor size (Table 2)

How do we calculate monitor ratio?

Monitor Ratio=Monitor Size/Diagonal of Sensor Size

(The unit should be the same. For screen: 1 inch=25.4mm, for sensor: 1 inch=16mm.)







The formula for calculating microscope on-screen total magnification is:

M(Total magnification on Monitor)=M(Objective) ×M(Video Adapter) ×Monitor Ratio

As shown above, the magnification of the objective lens is 40x, and the magnification of the video adapter is 0.5x. If we use a 12-inch screen and a 1/2 senor, then 40×0.5x(12×25.4/8)=762x, this is the total magnification on monitor.

If you have any question about calculating the total magnification of a microscope, please feel free to contact us.

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