How to centre a microscope darkfield condenser

How to centre a darkfield condenser

Darkfield microscopy is a technique that uses oblique lighting and a dark background to illuminate hard-to-see samples.

If you’re going to get the best out of your darkfield condenser, you need to make sure it’s properly centred.

The centering process is simple, but there are some slight differences between dry and oil darkfield condensers.

Centering a dry darkfield condenser

  1. Rotate your 10x objective lens into the viewing position. (This is the lens with the yellow ring around it)
  1. Remove one of the eyepieces from your microscope. Looking down the eyepiece-less ocular port, you’ll be able to see an image of the condenser and the dark or opaque disk in the middle of it.
  1. Adjust the height of the condenser and the stage until the dark disk almost covers the viewing area. (You want to be able to see a ring of light around the outside of the disk.)
  1. Adjust the centering screws of your condenser until the dark disk is in the dead centre of the ring of light. (The silver centering screws are usually found sticking out of the sides of the condenser. You can move the disk by rotating the screws back and forth.)

Centering an oil darkfield condenser

  1. Rotate your 40x objective lens into position. (This is the lens with the blue ring around it).
  1. Remove one of the eyepieces from your microscope. Looking down the eyepiece-less ocular port, you’ll be able to see an image of the condenser.
  1. Raise the condenser until you can clearly see a dark circle. The circle might appear a little fuzzy around the edges.
  1. Adjust the centering screws on your condenser until the dark circle is in the dead centre of the viewing area. (As with the dry condenser, the silver centering screws are usually found sticking out of the sides of the condenser. You can move the dark circle by rotating the screws back and forth.)

That’s all it takes – your condenser is centered and ready to go!

 

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