How to Focus a Microscope & How the Field of View Changes

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In this video I'm going to demonstrate how to focus the microscope.

Begin by turning your microscope on and

adjusting the light intensity to about five or six.

Then place your slide in the clamp on the stage and center the specimen over the condenser.

Then turn the low power objective into place and use the course focus

to move the stage all the way to the top.

While looking through the objectives, slowly turn the course focus down

until you can find your specimen.

When you think you've found it, wiggle the stage a little bit to make sure what you're focusing on actually moves with the slide.

If you wiggle the stage and nothing moves, you're focused on the wrong plane.

Once you've focused at 10x, you're going to rotate the next power into place-- the 40x.

This time use only the fine focus to adjust the stage and focus on your specimen.

You should not need to turn this focus more than one complete rotation.

Once you focused on your specimen at 40x,

now you're ready to move up to oil immersion. Turn the forty x objective out of the way

and put a drop of immersion oil over your specimen.


then rotate the 100x objective into position.

And it should touch

the drop of oil.

Once you have the 100x in position, use the fine focus to focus on your specimen at 100x.

When you're done, be careful to turn the objective out of the way before you lower the stage. Clean your microscope and put it away.