A revolving nose piece is found on a microscope and can be rotated to change power. There are at least two lenses in the revolving nose piece, also sometimes referred to as the turret.
A compound microscope is made up of many different parts, all of which work together to enlarge the image. There are two lenses:
- Ocular lens - the lens in the eyepiece into which a person looks
- Objective lens - the lens closest to the object
The objective lenses are found on the revolving nose piece. There are usually four lenses, but may be as few as two. The most common magnifications of the lenses are 4x, 10x, 40x and 100x. Users of the microscope should keep in mind that the final magnification is a combination of the objective lens' magnification and that of the ocular lens.
To make it easy to focus, the microscopes have a focus knob. First, however, the user should start with the lowest power objective lens and get the object into focus by moving the lens up and down. The focus knob is only used to fine tune the image. After the image is in focus with the lowest power lens, it should remain in focus with the high power lenses. It may be necessary to do some fine tuning with the focus knob, but there is usually no need to move the lens up or down.