Magnification and calibration

key equations and conversions

image size = actual size x magnification

key conversions

Calibration

  • eyepiece graticule

    • on the eyepiece lens

    • scale must be calculated using stage micrometer

    • always viewed as the same size

  • stage micrometer

    • known scale (often 10mm with 0.1mm divisions or 1mm with 0.01 divisions)

    • used to calibrate eyepiece graticule to measure your specimen

    • size varies with magnification

  • the aim is to find how many stage micrometer divisions there are per 1 EPGU

  • 1 EPGU = # of stage micrometer divisions / # of eyepiece graticule divisions (use ratio method - x smd :1 epgu)

worked example