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How to Calculate the Magnification of a Monocular Zoom Microscope?

05 May 2022

In previous articles, we talked about how to calculate the magnification of a microscope and how to calculate total video monitor magnification. (

The formula is as follows:

For optical microscopes:

Total Magnification = Eyepiece Magnification*Objective Magnification

For digital microscopes:

Total Magnification = Video Adapter Magnification*Objective Magnification* Monitor Ratio

Monitor Ratio=Monitor Size/Diagonal of Sensor Size

In this article, we will discuss the calculation of the magnification for the monocular zoom microscope which with modern design concept, high resolution, long working distance and large magnification. They are mainly used in electronic industry, small precision parts inspection, assembly, repair, especially for observation for surface structure. They can also be applied to biological anatomy, jewelry inspection, and schools academic use.

The following is the formula:

Total Magnification (M) = Total Optical Magnification*Monitor Ratio

The optical magnification here includes three parts: the magnification of the zoom body, the magnification of the objective lens and the magnification of the video adapter. which is:

Total Optical Magnification = M(Zoom Body)*M(Objective) *M(Video Adapter)

The calculation method of monitor ratio is the same. It should be noted that the unit should be unified in the calculation process: for screen: 1 inch=25.4mm, for sensor: 1 inch=16mm.

Taking the product BS-1085A with auxiliary lens 1X, C-mount 1.67X as an example, the magnification of the zoom body is 0.3X-3X.

Then the total optical magnification is as shown:

Total Optical Magnification (Max.) = 3*1*1.67=5X

Total Optical Magnification (Min.) = 0.3*1*1.67=0.5X

Choose an 11.6-inch LED screen and BHC4-4K8MPB microscope camera with a sensor size of 1/1.2 inch. Remember that the magnification of the C-mount should match the size of the camera sensor to ensure a good field of view. Usually, the sensor size matched by the C-mount of 1X is less than 1 inch. The screen display magnification is:

Monitor Ratio = 11.6*25.4 /(1/1.2*16) = 294.64/13.33 = 22X

The total maximum and minimum magnifications can be calculated now:

M (Max.) = 5* 22= 110X

M (Min.) = 0.5*22= 11X


The modular design of monocular zoom microscopes can be connected to a variety of stands, illuminators, objectives and C-mounts, so that different magnification requirements can be customized.

In the use of monocular zoom microscopes, the field of view is also a parameter to be considered. The range of the field should be selected according to the size of the observed specimen, and the field of view depends on the magnification. The higher the magnification, the smaller the field of view. The calculation formula is as follows:

Field of View = Diagonal of Sensor Size / Total Optical Magnification

For example, the above microscope calculates that the maximum field of view is 26mm (1/1.2*16/0.5), and the minimum field of view is 2.6mm (1/1.2*16/5). The FOV can be adjusted according to the size of the specimen to achieve better observation.

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


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