When focusing a microscope, which objective should you start with?

Starting with the lowest power objective, such as 10X, is essential when focusing a microscope for several reasons. The lower magnification provides a wider field of view, making it easier to locate the specimen you are examining. It also allows for a greater depth of field, which is beneficial for obtaining a clear view of the sample, especially when the thickness of the specimen varies.

Using a higher magnification objective initially, such as 40X or 100X, can lead to difficulties in locating the specimen and make it more challenging to focus correctly, potentially risking damage to the slide or the objective lens. Once the specimen is centered and in focus under the lower power, one can then switch to a higher power objective for a more detailed examination. This systematic approach ensures that you maintain control over the focusing process and minimizes the risk of mishaps.