sinar bellows extension calculator

hi All

i just picked up a Sinar calculator but it has no instructions

i understand the concept and that i place the cap in shot then measure its length
but it’s not clear where the scale starts on the body

Attachment 203749

do I in measure from the end or from one side or the other of the white square

best

robin

Try this....

I believe you lay the pen on the ground glass, oriented to the right 0 point of the cap image.

Then read the bellows factor out directly comparing the two.