scope:

This International Standard specifies the dimensions of screw thread types for connecting a microscope objective to the nosepiece.

NOTE 1 The use of these screw thread types is recommended for microscopes unless other fittings are required for optical or design reasons.

NOTE 2 A specific combination of eyepiece, objective and tube lens (if provided, e.g. in an infinity-corrected optical system) is frequently used to correct aberrations. Therefore the combination of an objective from one manufacturer and the tube lens or eyepiece from another manufacturer, although conforming to this International Standard, may cause error in magnification and/or loss of image quality.