The coarse focus knob on a microscope is used to bring the specimen into a rough focus range by rapidly adjusting the focus of the microscopes objective lens. It is larger than the fine focus knob and moves the objective lens in larger increments, making it suitable for quickly bringing the specimen into view and starting the focusing process. The coarse focus knob should always be used first, before adding the slide to the mount, and only for the lowest-power lenses. On most microscopes, the coarse adjustment knob is located along the lower middle part of the arm of the microscope and is the bigger of the two knobs, located closest to the arm of the microscope. It should not be used with high-power objectives, as it raises and lowers the stage too quickly, making it difficult to maintain focus.