When
ordering the IMA Graticule specify the diameter (in millimeters)
of the graticule disc to fit your microscope eyepiece and the
magnification factor (MF). The MF is unique for each microscope
and 10x objective combination. Determining the correct MF value
insures that the sizing circles will be exactly 10 and 25 microns+/-2%
on your microscope. The MF value is calculated as follows:

1.
Set up the microscope with all the attachments and lenses you
will use during the IMA. The IMA requires a compound microscope
with a 10x objective, two 10x eyepieces and episcopic (vertical)
illuminator, IMPORTANT! To calculate a correct MF value the episcopic
(vertical) illuminator must be installed along with the other
attachments affecting the microscope tube length/magnification
(anything placed between the objective and the eyepiece).

2.
Insert a 100 division/10mm graticule scale into one eyepiece.
Many microscopes are purchased with such a scale already installed.

3.
Adjust the interpupillary distance.

4.
Adjust the magnification to 100x by moving the 10x objective into
place.

5.
Turn on the microscope's illumination and focus the eyepiece so
that the graticule lines are clear and sharp. Rotate the eyepiece
diopter ring to focus, not the microscope focus knob.

6.
Place a certified stage micrometer of 100 division/1mm on the
microscope stage and focus the microscope on the graduated lines.

7.
Adjust the microscope stage x & y controls to align the stage
micrometer parallel with the eyepiece graticule scale at the zero
division.

8.
Record the largest number of whole eyepiece graticule scale divisions
(GSD) per corresponding whole stage micrometer division (SMD).
To make the measurement as accurate as possible a large part of
each scale must be used. The ratio of eyepiece graticule scale
divisions/stage micrometer divisions is the magnification factor
(MF).

9.
Examples

If there are 75 GSD per 80 SMD then MF = 0.938 or (75/80)

If there are 95 GSD per 92 SMD then MF = 1.032 or (95/92)