An undergraduate student is using a standard compound light microscope to study onion epidermal cells. They have successfully focused on a group of cells at a total magnification of ×100 \times 100\,×100 using the ×10 \times 10\,×10 objective lens.
Describe the step-by-step procedure the student must follow to safely increase the total magnification to ×400 \times 400\,×400 and obtain a sharp image.
