What is the part of a microscope that will sharpen the focus of an image? It has 13 letters and ends with an E

Answer 1

Are you sure about it ending with E? It could be the fine focus knob.

There is also a coase focus knob but that has too many letters. Inexpensive microscopes have only one fcus knob.

Answer 2

projector lens and objective lens

are both 13 letters but no e at the end.