There is a scale on the plane of the field diaphragm of the E10S's 10x magnification eyepiece. It can be used as a normal eyepiece with 10x magnification, which is also suitable for measuring the size of objects or their elements. The scale is marked in millimeters and microns. If you want to take measurements, you must first calibrate the eyepiece for each objective you intend to use. The eyepiece of the E10S fits into a 23.2 mm tube.

Calibration

To carry out the calibration, a calibration slide with a scale of 0.01 mm is required. Place the slide on the stage and focus the microscope on its scale. Then rotate the eyepiece in the tube until the divisions on the slide and the eyepiece scales are parallel. After that, you need to do a calculation.

Calculation

You need to calculate how the divisions on the eyepiece scales and on the calibration slide (aka stage micrometer) relate to each other: how many divisions on the eyepiece scale fall on the slide scale (for low magnification objectives) and how many divisions on the slide fall on the eyepiece scale (medium or high magnification lenses). After that, use the following formula:

- E = TL/A, where
- E is the division of the eye lens scale
- T is the scale division of the stage micrometer, marked on the stage micrometer (0.01 mm)
- L is the number of divisions on the stage micrometer
- The number of divisions on the eyepiece scale

Record the resulting number for each lens.
The size of the samples should be calculated as follows: first, determine how many divisions it occupies on the lens scale. This number must be multiplied by the result obtained from the formula for each lens. This number shows the linear value of the sample.

Specifications
- Lens material: optical glass
- Degree of magnification, multiplier: 10
- Field of view diameter, mm: 20
- Diopter adjustment: −
- Division, mm: 0.1
- Eyepiece diameter, mm: 23.2
- Frame material: copper
- Eye distance, mm: 10

Compatibility
- MAGUS Bio 230B biological microscope
- MAGUS Bio 230BL biological microscope
- MAGUS Bio 230T biological microscope
- MAGUS Bio 230TL biological microscope
- MAGUS Pol 850 polarizing microscope