I have a bunch of nice objective lenses from an huge old microscope set, and would like to make a microscope body tube with just one objective and one ocular lens. Without using trial and error to determine the right distance between the lenses, how might I calculate the correct distance between them. I'm then going to make a tube with this length and with a thread so I can mount the objective lenses. For the ocular lens I want to use an adapter from AmScope (CA-NIK-SLR) which mounts directly onto a DSLR camera.
I've tried to use a rolled up paper to determine a good distance from the objective lens to the camera, but I can't tell if the image is focused correctly on the camera sensor. Even if I could tell, I can't easily measure it then. Trial and error for this would take a lot of time and money and so I'd prefer it if I can get a formula or something like that.
If anyone knows how to do that, I'd be really happy to hear it!