how do you work out the focul distance on a camera eg like you would see on binoculas etc. eg 10x / 12x?

Answer 1

The measure of focal length in camera lenses is given in mm. It is not usually stated the same as for binoculars.

If you want a rough estimate, 50mm is about normal eyesight size. So a 200 mm telephoto setting is about 4x in binoculars.