Biology » Introducing the Cell » Molecular Make Up Of Cells

Using a Microscope

How to Use a Microscope Correctly

  • When handling or carrying the microscope, always do so with both hands. Grasp the arm with one hand and place the other hand under the base for support.
  • Turn the revolving nosepiece so that the lowest power objective is in position.
  • Place the microscope slide on the stage and and fasten it with the stage clip(s).
  • Look through the eyepiece and adjust the diaphragm for the greatest amount of light.
  • While looking at the slide on the stage from the side, turn the coarse adjustment screw so that the stage is as close to the objective lens as possible. WARNING: Make sure you do not touch or damage the slide.
  • Slowly turn the coarse adjustment screw until the image comes into focus.
  • Now use the fine adjustment screw to move the stage downwards until the image is clearly visible. Never move the lens towards the slide.
  • You can readjust the light source and diaphragm for the clearest image.
  • When changing to the next objective lens use the fine adjustment screw to focus the image. WARNING: Never use the coarse adjustment screw for the strongest objective lens.
  • Do not touch the glass part of the lenses with your fingers.
  • When finished, move the stage and objective as far away from each other as possible and remove the slide.
  • Disconnect the power source and cover the microscope.
  • Carry the microscope by holding it firmly by the “arm” and “base” and when walking it should be near your chest.

Image Credit: Shutterstock


Remember that microscopes are expensive scientific equipment and need to be handled with care to prevent damaging them. Proper lens paper should be used when cleaning dust or dirt off any lenses. Avoid getting moisture on the objective lenses. Dust and moisture are the biggest enemies of microscopes.


WARNING: if using a mirror for illumination instead of a light bulb, never reflect direct sunlight as you could damage your eyes.

PropertyLight MicroscopeTransmission Electron Microscope
SourceLightBeam of electrons
Resolution (how far apart two objects must be in order to be distinguished as separate)Under optimal conditions (clean lenses, oil immersion), the resolution is 0,2 micrometres or 2 thousands of a millimetreResolution of a transmission electron microscope is about 0,05 nanometres (nm) which is about 0,5 millionth of a millimetre. This means that a transmission electron microscope has about 10 000 times the resolving power of a light instrument
Material (alive/ dead)Alive or dead. Bright field or phase contrast microscopes enable viewer to observe living cells. Specimens need to be stained.Dead. Electron microscope images are produced by passing an electron beam through tissues stained with heavy metals.
Example of microscope image

Bacterial spores as seen under light microscope.


Chlamydomonas reinhardtii, a single celled green algae, as seen under the transmission electron microscope.

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