Magnification and Lateral Magnification

The total magnification of the microscope is calculated from the magnifying power of the objective multiplied by the magnification of the eyepiece and, where applicable, multiplied by intermediate magnifications.

A distinction is made between magnification and lateral magnification. 

While the magnification always refers to the impression of the eye, the lateral magnification is always a measurable value. If an object is viewed with the eye from a distance of 250 mm, the magnification is 1x. If the distance is 500 mm, the size of the object seen is halved - the magnification is reduced to 0.5x. The viewing angle under which something is seen is a decisive factor. When looking into the microscope, the viewing angle under which the object is seen is increased precisely by the factor resulting from theabove calculation of the total magnification. This does not mean that the entire viewing angle is also imaged in the eye! The viewing angle is limited by the field of view. 

The term lateral magnification is always used if an image is produced which is to be measured using a scale. For example, a photo is taken using a microscope camera and the size of an object detail in the specimen determined. For this, the detail on the photo is measured using a scale. If this length is divided by the total magnification, the original size is obtained. Example: Object size 10 mm on the paper photo, taken with objective 40x, phot eyepiece 10x, camera magnification 0.25x and additionally magnified 4x from the negative. 

10 mm


40 x 10 x 0.25 x 4 

The result is 0.025 mm or 25 µm. The size of the object detail therefore was exactly 25 µm. The lateral magnification is 400:1. If the photo is viewed from a distance of 250 mm, it appears to be 400 times as large, as if the object detail on the microscope slide were viewed with the naked eye.