How to operate the coarse and fine focusing knobs of a tool microscope
Using a quasi focal spiral to adjust the focal length and find the object can be said to be the most important step in the use of a tool microscope. Never make the following errors during operation: first, focus directly under high magnification; The second is that regardless of whether the lens barrel rises or falls, the eyes are always looking at the field of view through the eyepiece; Thirdly, there is a lack of understanding of the critical value of object distance. When the object distance is adjusted to 2-3 centimeters, it is still increasing upwards, and the speed of rotating the quasi focus spiral is very fast. The first two types of errors often cause the objective lens to collide with the mounting, damaging the mounting or lens, while the third type of error is a common phenomenon when using a microscope.
To adjust the focal length, it is necessary to lower the lens at low magnification. First, rotate the coarse focus screw to slowly lower the lens barrel and bring the objective lens closer to the glass slide, but do not let it touch the glass slide. During this process, the eyes should look at the objective lens from the side, then use the left eye to look into the eyepiece, and slowly adjust the coarse focus screw in reverse to slowly raise the lens barrel until the object image is seen. At the same time, the object distance of a microscope is usually about 1 centimeter. Therefore, if the object distance has exceeded 1 centimeter but the object image is still not seen, it may be that the specimen is not in the field of view or the coarse focus screw is rotating too fast. At this time, the mounting position should be adjusted, and then the above steps should be repeated. When a blurry object image appears in the field of view, it is necessary to switch to a fine focus Accurate focus spiral adjustment is the only way to narrow down the search range and improve the speed of finding the object image.
