Answer:
he forgot to adjust the brightness and the curtain. Slowly move the knob so that the objective goes up. Continue until the image is okay
Pretty clear focus. Then use the knob, if available, for a clearer picture. If you are on a microscope with a moving specimen carrier, turn the coarse knob so that the table carrying the specimen moves down or away from the objective. This is exactly how to use a microscope focus regulator.
Explanation: