Definition of Magnification in Microscopy

••• Image by, courtesy of Matthew Hine

Microscope magnification is how large the object will appear compared to its actual size. Technically, magnification compares the actual angular size of an object to the actual angular size of the object if it was viewed at a distance of 25 centimeters.


Light microscopes have two lenses: the eyepiece and the objective lens. The eyepiece is at the top of the microscope. The objective lens is at the bottom of the body tube next to the stage. Many microscopes have several objective lenses of different magnification that can rotate into place.

Magnification Location

The magnification for the eyepiece can be found on the eyepiece itself. The magnification for the objective lenses can be found on each objective lens. The overall highest magnification is written on the side of the body tube.

Finding the Overall Magnification

To find the overall magnification of the microscope, multiply the magnification of the eyepiece by the magnification of the objective lens you are using. For example, if the magnification of the eyepiece is 10x and the magnification of the objective lens is 40x, the overall magnification is 400x.

Magnification and Resolution

Generally, the higher the magnification of a microscope, the higher the resolution. The resolution at 10x is equal to 0.7 microns. The resolution at 100x is 0.2 microns.

How to Adjust Magnification Properly

Mount the slide on the microscope, view it at the lowest magnification and get it in focus. Then increase the objective lens magnification by one step. Adjust focus. Repeat this process for each step up in objective lens magnification.


About the Author

Corina Fiore is a writer and photographer living in suburban Philadelphia. She earned a B.S.Ed. in Earth-Space Science from West Chester University of Pennsylvania. Fiore taught high school science for 7 years and offered several teacher workshops to regarding education techniques. She worked as a staff writer for science texts and has been published in Praxis review materials for beginning teachers.

Photo Credits

  • Image by, courtesy of Matthew Hine

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