Final answer:
Focusing distance is associated with the working distance of a microscope objective lens. The working distance is the distance between the lens and the specimen on the slide. Lenses on a microscope are parfocal, allowing for easy switching between lenses without major adjustments.
Step-by-step explanation:
Focusing distance is associated with the working distance of a microscope objective lens. Working distance is the distance between the objective lens and the specimen on the slide. As you increase the magnification, the working distance decreases. However, the lenses on a microscope are designed to be parfocal, meaning that the object should remain nearly in focus when switching between lenses.