what does the nosepiece do on a microscope

The nosepiece, also known as the revolving nosepiece or turret, is a circular structure located between the ocular lens (eyepiece) and the stage of a microscope. It holds two or more objective lenses and can be rotated to easily change the magnification power. Most microscopes have three or four cone-shaped lenses attached to the nosepiece. The main purpose of the revolving nosepiece is to easily and systematically interchange the objective lenses. Objective lenses come in increasing magnifications, and depending on the microscope, the nosepiece can hold anywhere from 3 to 5 objectives. The revolving nosepiece is a time-saving and integral part of the working of a microscope, as it enables the microscope user to quickly change objective lens magnifications while keeping the specimen centered. Sophisticated microscope nosepieces lock the objective lens into place with such precision that the objective stays in alignment and completely centered with the specimen, eliminating the need to re-position a slide and reducing the time to focus.