Re: What does the fine adjustment do in a microscope?

The role of fine adjustment is to move the Objective lense with a finer 
movements. The object under observation is brought to the focus by 
adjusting the distance between the Objective lens and the object. While 
using higher magnifications, it is this distance is very critical and 
slight variation makes the image out of focus. Hence, it is very difficult 
to adjust the distance or in other words 'focus the image' using course 
focus. The fine adjustment option moves the Objective lens to very less 
distances per turn of the knob allowing the user to bring the object into 
the focus.

Apart form the fine adjustment, which moves only the objective lens, it is 
also sometimes necessary to adjust Concensor light source to get better 
contrast. Also, good microscopes are equipped with eye distance and eye 
balance adjustments to suit individual eye sights.