Final answer:
A pledger is not a term associated with parts of a microscope. Microscopes have objective and ocular lenses and use coarse.
Step-by-step explanation:
The objective lenses on a light microscope are closest to the specimen and vary in magnification, typically from 5x to 100x. These lenses are mounted on a turret and are parfocal, meaning that when you switch between objectives, the sample remains in focus.
The ocular lens or eyepiece generally has several lenses within a cylindrical barrel and functions to further magnify the image, contributing to the final magnification together with the objective lens.
The focusing ability in a microscope is through the coarse and fine focusing knobs, where the coarse knob allows for large-scale adjustments, particularly with the lower magnification lenses, and the fine knob allows for precise focusing, especially at higher magnifications.