The objective at the highest position, the 4x objective should of course not touch the slide. Close the condenser and looking through the eyepiece lower the stage using the coarse focus until you see a clear image. Only rotate the coarse focus into one direction and stop when you see a clear image.
When viewing a clear image, if you don’t turn it down it will increase the lens in which this is when you should stop using the course adjustment knob on the compound microscope. You should stop using it because it will break the glass/sample.
Knowing the difference between fine adjustment and coarse adjustment knobs on the microscope is an integral part of focusing the microscope. The coarse adjustment knob quickly gets the image in focus and the fine adjustment knobs help keep the image in focus under progressively higher magnifications.
In order to move your microscope safely, one hand should be under its base for support and the other at its arm. Be sure to only switch off the microscope when the dimmer is set to the lowest intensity and always turn off the lamp before moving the microscope. So now you know how to use and adjust a compound microscope. Well done.
If your eyepiece (s) on your microscope is built facing away from the arm of the microscope then turning the knob away from you will raise the stage and turning the knob towards you will lower the stage.
What should you always remember when you use the coarse adjustment? You should always remember when you use the coarse adjustment to used to focus the microscope but only used it with the low power objective.
The gearing mechanism of the adjustment produces a large vertical movement of the stage with only a partial revolution of the knob. Because of this, the coarse adjustment should only be used with low power (4X and 10X objectives) and never with the high power lenses (40X and 100X).
When using 10x and 40x objectives, use ONLY the fine focus knob so that you don't scratch a lens or break a slide. Always carry your microscope with one hand under the base and one hand on the arm. Some microscopes may have a mirror as the light source.
The coarse adjustment knob is used ONLY with the low power (4X, 10X) objectives. When focusing under the 40X or 100X objective, ONLY use the fine adjustment, never the coarse adjustment.
Here are step-by-step instructions on how to use and adjust a compound microscope: Turn on the illuminator. When using the dimmer, it is best slowly increase the light intensity as the lamp heats up quite quickly. Place a slide or specimen on the stage with the sample directly above the aperture and, if possible, ...
Some compound microscopes come with what is called a rack stop. A rack stop prevents the objective lenses from being lowered into the slide. However, some older microscopes do not have a rack stop, so it is always advisable to check, just in case.
Lowering an objective lens into a slide could easily break the slide and damage the sample. In order to move your microscope safely, one hand should be under its base for support and the other at its arm.
If you focus the high power objectives with the coarse focus knob, then you risk slamming the objective into the slide, risking the damage of both. Some high power objectives are spring-loaded, with a front-part that retracts when touched by the slide. This is a protective mechanism.
If you look at a specimen under high power and then directly exchange the slide, you run the risk of losing focus again . The thickness of the mounting medium is not always the same and also the position of the specimen in the mounting medium can be different. Using the coarse (and even the fine focus) will take longer than starting again with the 4x objective and the coarse focus.
The 4x objective also allows you to center the slide better, because it gives you a better overview. The 4x also has the greatest depth of field and this means that the whole specimen (top and bottom parts) are in focus. If you start with a high power objective and then start focusing, then you don’t know if you are focusing at the actual specimen or on the dust which is on the top of the cover glass.