If you cannot focus at 100X, what is the recommended sequence?

If you cannot focus at 100X, what is the recommended sequence?

• A. Go to 10X using the course knob, then back to 100X
• B. Return to 40X and refocus
• C. Switch to 4X and adjust diaphragm
• D. Shut down and restart

Answer: (A)

When focusing at high power, the image depth is extremely shallow, so small changes can push the image out of focus. If you can’t get a sharp view at 100X, re-establish rough focus at a lower magnification using the coarse adjustment knob (for example, switch to 10X and bring the specimen into rough focus). Then switch back to 100X and use the fine adjustment to sharpen the image. This approach minimizes the risk of crashing the objective into the slide and helps you quickly relocate the correct focal plane. Adjusting the diaphragm or switching to 4X doesn’t directly fix high-power focusing, and restarting isn’t needed.

When focusing at high power, the image depth is extremely shallow, so small changes can push the image out of focus. If you can’t get a sharp view at 100X, re-establish rough focus at a lower magnification using the coarse adjustment knob (for example, switch to 10X and bring the specimen into rough focus). Then switch back to 100X and use the fine adjustment to sharpen the image. This approach minimizes the risk of crashing the objective into the slide and helps you quickly relocate the correct focal plane. Adjusting the diaphragm or switching to 4X doesn’t directly fix high-power focusing, and restarting isn’t needed.