Question

Manipulate: With 40x selected, use the Coarse and Fine focus sliders to focus on the sample. Then, choose 400x and focus on the sample using the Fine focus Slider.
A Which focus knob is easier to use at 40x?
400x?

Answer 1

- At 40x the coarse focus knob is easier to use for getting the image into rough focus (then use the fine knob for small sharpening).
- At 400x the fine focus knob is easier — and should be used — because high magnification has a very small depth of field and the coarse adjustment moves too much (you’ll overshoot or risk crashing the objective into the slide).