How to Calculate Field of View of a Compound Microscope?

What is Field of view (FoV) of a microscope?

Field of view is how much of our specimen we will be able to see through a microscope. It is simple the observable area in millimeters that we see through the eye piece of the microscope.

Field of View (mm) = Field Number of Eye piece (FN) ÷ Objective Magnification

What is Field number of a microscope?

The field number (FN) in microscopy is the diameter of the image area that can be observed through the eyepiece. 

Filed number is inscribed on the eye piece along with the magnification.

For example, an eyepiece with a magnification of 10x typically has a field number ranging between 16 and 18 millimeters, while a lower magnification eyepiece (5x) has a field number of about 20 millimeters. Watch our video for better understanding.

Let us calculate FoV of a microscope. See the table given below.

In this example; Suppose the eye piece is of 10X magnification, if we view the specimen in low power objective that is 10X; 

In the given example the field number is 20 as given in the eyepiece (circled in red color in the figure).

Field of View (mm) = Field Number of Eye piece (FN) ÷ Objective Magnification

                                =20/10=2mm

The calculation with 40X and 100X objective is given in the table. Hope you are clear. 

Learn more:

Ten Types of Microscope

Thank you so much.