Measurement with the
Microscope
Key Terms
• Field of View (FOV)
– The diameter of circular image seen through a
microscope.
– Usually measured in micrometers (μm)
White Blood Cells seen
through a microscope
FOV
…Key Terms
• Fit Number
– The number of times a specimen will fit
across the field of view. i.e. 2, 4, 3.5.
– What is the fit number of the white blood cell
shown below…?
…Key Terms
• …Fit Number
– This cell will fit across the field of view
approximately 5.3 times.
– Fit number is 5.3
…Key Terms
• Scaled Magnification (SM)
– Scaled magnification refers to how much
bigger your drawing is than the actual image
– If the actual image is 0.2 mm and your
drawing is 20 mm, then SM = 100X
– SM is NOT the same as ‘magnification’.
Formulas
How to calculate an unknown
Field of view (FOV)
Determine FOV on low power as instructed by your teacher
Unknown FOV size = known FOV on low power X magnification on low power
magnification at unknown FOV
How to estimate the size
of a specimen in a field of view
size of specimen (in µm) =
How to determine the scaled
scaled magnification =
field size (in µm)
“fit number”
magnification
diagram size (mm)
actual size (mm)
Don’t forget to
use the same
units within the
same formula!