Coarse focusing knob

Definition

The coarse focusing knob is a part of the microscope used to bring the specimen into general focus. It moves the stage or objective lens quickly and over a large distance.

5 Must Know Facts For Your Next Test

1. The coarse focusing knob is primarily used with lower magnification objectives.
2. It should not be used with high-power objectives to avoid damaging the slide or lens.
3. Turning the coarse focusing knob adjusts the distance between the objective lens and the specimen.
4. It is often larger than the fine focusing knob and located on both sides of the microscope for ease of use.
5. Using the coarse focusing knob first helps achieve a rough focus before fine adjustments are made with the fine focusing knob.

Review Questions

• When should you use the coarse focusing knob during microscopy?
• Why is it important not to use the coarse focusing knob with high-power objectives?
• How does turning the coarse focusing knob affect your view of the specimen?

Related terms

Fine Focusing Knob: A smaller knob used to make precise adjustments to focus after using the coarse focus.

Objective Lens:

Lenses on a microscope that magnify specimens at different levels; typically include low, medium, and high power options.

Stage:

The flat platform where slides are placed for observation under a microscope.