The coarse adjustment knob brings the specimen into general focus on a microscope.

Here's why:

* Coarse Adjustment: This knob moves the stage up and down in large increments. It's used to bring the specimen into approximate focus, usually when you're starting with a new slide.

* Fine Adjustment: This knob moves the stage in very small increments, allowing for precise focusing once you've achieved general focus with the coarse adjustment.

So, the coarse adjustment gets you close, and the fine adjustment gets you sharp!