Final answer:
The parfocal view-area is the part of a specimen that remains in focus when switching between different magnification levels on a microscope with parfocal lenses, minimizing adjustments and providing a streamlined viewing experience.
Step-by-step explanation:
The term parfocal view-area refers to the field of view that remains in focus when switching between different magnification levels on a microscope with parfocal objectives. On a parfocal microscope, minimal adjustments are required when changing from low to high power objectives, making the microscope user-friendly and efficient for viewing specimens.
Microscopes are designed this way to aid in observation, allowing scientists and students to quickly switch between different magnifications while maintaining clear vision of their sample. Parfocality is essential because it ensures a smooth transition and a consistent working distance, which is the space between the objective lens and the specimen. The objective lenses, typically ranging from 5x to 100x magnification, work together with the eyepiece or ocular lens to magnify the specimen and present an enlarged image to the observer.