Field Notes Journal a personal natural history of place

0.4 Calibration of the Eyepiece Graticule

Aim

To establish the scale value of the eyepiece graticule for measurement.

Specimen & Apparatus

• Stage micrometer slide
• Eyepiece graticule
• Compound microscope

Method

1. Insert the eyepiece graticule into the eyepiece.
2. Place the stage micrometer on the stage and bring into focus.
3. Align the graticule scale with the micrometer scale.
4. Determine how many graticule divisions correspond to a known length on the micrometer.
5. Repeat for each objective lens.

Observations to Make

• Number of graticule divisions matching known micrometer distances.
• Variation in scale value between objectives.
• Consistency of alignment across the field.
• Ease or difficulty of precise alignment.