At 4x magnification, which step can be skipped, especially with bacteria?

At 4x magnification, which step can be skipped, especially with bacteria?

• A. Focusing with course knob
• B. Adjusting brightness
• C. Changing objective
• D. Moving the slide

Answer: (A)

At low power (4x), the field of view is large and the depth of field is relatively thick, so you can bring the image into view and sharpen it with fine focus rather than making large jumps with the coarse adjustment. The coarse knob moves the stage a lot, which can overshoot the focal plane or destabilize a delicate bacterial smear. By relying on fine focus at this magnification, you can gently fine‑tune the focus to clearly see the bacteria without risking losing the focal plane or causing slides to crash. Once you’re ready for more detail, you can switch to higher magnification and continue with precise fine focusing.

At low power (4x), the field of view is large and the depth of field is relatively thick, so you can bring the image into view and sharpen it with fine focus rather than making large jumps with the coarse adjustment. The coarse knob moves the stage a lot, which can overshoot the focal plane or destabilize a delicate bacterial smear. By relying on fine focus at this magnification, you can gently fine‑tune the focus to clearly see the bacteria without risking losing the focal plane or causing slides to crash. Once you’re ready for more detail, you can switch to higher magnification and continue with precise fine focusing.