48
Graticule 10 mm/100 divisions (63)*
For graticules with a scale of 10 mm/100 divisi-
ons, one scale interval is roughly equivalent to
the following lengths in the specimen plane:
0.02 mm = 20 µm for 5 x objective
0.01 mm = 10 µm for 10 x objective
0.005 mm = 5 µm for 20 x objective
0.002 mm = 2 µm for 50 x objective
0.001 mm = 1 µm for 100 x objective
Graticule for standard series/Snyder-Graff (64)*
The graticule for the standard series and Snyder
Graff methods contains a centre circle which
frames an image area of 80 mm for the standard
magnification.
The image area of 80 mm diameter corresponds
to the grain images of standard series charts and
enables exact comparison of grain sizes.
The centre circle can also be used for grain size
determinations with the circle segment or area
count methods.
The graticule also has a reference length for the
Snyder Graff method.
This method involves counting the number of
grains intersected by the reference line and then
calculating the average grain size from several
measurements.
ASTM-E-112 graticule (65)*
The ASTM-E-112 is divided up into 8 segments
with labelled grain size pictures.
The pictures conform to grain sizes plates no. 1A
and 1B of the ASTM-E112 standard.
For reasons of space, the graticule contains 8
representative circular grain size images from a
total of 22 of the above-mentioned plates 1A and
1B.
Fig. 63
Graticule with 10 mm/100 divisions
Fig. 64
Graticule for standard series/Snyder Graff
Fig. 65
ASTM-E-112 graticule