Take a picture of a ruler or micrometer slide (depending of magnification).iconoclastica wrote:How do I determine the tube factor?
The relationship between the image size on the sensor and the object size is the total magnification.
Divide it by the objective magnification and you have it.
- Do it at the right focusing point, the position where changing objectives the system is parfocal
- If you use direct projection you will have the head magnification factor, if you use a relay lens you need to take it in the account.
If you want to know the tube factor with the eyepieces the procedure is the same but taking the eyepiece field diameter ("field number") as reference in place of the sensor size.