（１）Shooting with the USB camera of microscope connected to the 3rd eye
There are scales on the software.
The pitch of the scale can be changed
The above picture is adjusted to divide the 0.1 mm width into 25 equal parts. (You can not put numbers on the scale.)
（２）Shooting through a reticle (glass scale) lens with a small digital camera
There is also a way to use ordinary digital camera and camera bracket.
Using this bracket, and attach a digital camera to the eyepiece of the microscope and shoot.
（３）Shooting with a microscope camera that covers the eyepiece
Place a eyepiece (glass scale) of the microscope.
Cover the eyepiece with a microscope camera that covers the eyepiece.
Then you can take pictures with a reticle (glass scale)