Steps of Using a Microscope

By Anne Mullenniex

Microscopy allows us to see fine details and organisms too small to be seen with the naked eye through magnification of objects with the use of fine-ground lenses, resolution and contrast. Most microscopes used in classrooms are binocular bright-field light microscopes that use visible light to view slides. Care and use of a microscope go hand in hand, beginning with carrying or moving the instrument to putting it away properly.

Step 1

Use both hands to move and place the microscope---one hand on the arm and the other on the base---and set it down gently into its final viewing position.

Step 2

Locate the coarse and fine adjustment knobs on the sides of your microscope. The coarse adjustment knob will be the larger knob closer to the arm of the scope, while the fine focus knob is the smaller knob sticking out of the coarse adjustment knob.

Step 3

Raise the condenser lens below the microscope stage to its highest position. This position will usually direct the highest quality of light through your specimen.

Step 4

Place your microscope slide with prepared specimen on the stage between the adjustable stage clips. Use the microscope stage adjustment knobs to center your slide.

Step 5

Adjust the binocular lenses to the distance between your pupils. Then, while looking through one lens at a time, make small incremental adjustments of each ocular lens until you can see as clearly as possible.

Step 6

Adjust the light adjusting dial to set the light source to the desired brightness while looking through the ocular lens at the specimen on the stage. Also move the iris diaphragm lever (below the condenser, under the stage) to further adjust the light.

Step 7

Find the specimen with the lowest objective lens in place, (usually a 4X). While looking through the ocular lens, use the coarse adjustment knob to bring your specimen into focus. Once the focus cannot be improved with the coarse adjustment, use the outer fine focus knob to fine-tune the focus. If your microscope has parfocal capability, then you will only need to use the fine focus knob as you increase magnification with the other objective lenses. Move the revolving nosepiece clockwise to each increasing magnification in order---typically to 10X, then 40X.

Step 8

Move the slide as needed, using the microscope stage adjustment knobs.

Step 9

Put the microscope away properly by turning off the light source, lowering the stage as far as it will go and leaving the lowest objective lens in place.

Tips & Warnings

  • Immersion oil is only used with 97X or 100X objective lenses--usually used to view bacteria.
  • Total magnification is the product of the objective lens magnification by the ocular lens magnification; so the combined total magnification provided by using a 4X objective lens and a 10X ocular lens is 40X.
  • Avoid jarring sensitive lenses and other components of the microscope by never sliding a scope across a surface nor dropping it onto a bench-top.
  • Only use lens paper to wipe any ground lens surface to avoid scratching the lens.

References & Resources