We avoid using the coarse focus knob with the 40x lens because it can lead to a high risk of crashing the lens into the slide, potentially damaging both the slide and the objective lens. The coarse focus knob moves the stage significantly, which is suitable for lower magnifications, but at high power, even small movements can cause contact. Instead, the fine focus knob should be used to make precise adjustments for clear imaging.
The depth of field is so small that a very small vertical travel could shift the focus from the top of the specimen to the bottom. A very fine adjustment must be used, which is why the coarse adjustment screw is implemented.
The fine focus knob is used to bring an object into fine focus, while the course focus knob is used to bring an object into approximate focus. The course focus knob should only be used on the low-power and scanning objectives of the light microscope. Using it on the high power microscope is okay, but you should be very careful. It is no recommended to use the course adjustment knob on the oil-emersion objective as it is so close to the stage and could lead to a potential break in the slide. Fine focus adjustment knob is useful to bring out the fine details in the specimen on your slide. Can be used on any of the objectives, but most receptive on the high-power and oil-emersion objectives.
The coarse adjustment knob on a microscope should never be used with the high-power objective lens. This can cause damage to both the lens and the slide being viewed. Instead, it is best used with the low-power or scanning objective lens for initial focusing.
First of all, one should never call it high power, it is morecommonly called the "high objective", yet that is not what this question is asking. To answer the question: You use the fine adjustment knob. This knob should be located near the coarse adjustment knob, on the opposite side of the microscope (at the same height as the coarse adjustment knob), or even as a separate knob protruding from the coarse adjustment knob. The fine adjustment knob is smaller in size. You should never, ever use the coarse adjustment knob under the high objective, you could scratch the microscope slide, cover slip, high objective lens, or in a worst case scenario break the high objective lens.
When changing from medium to high power on a microscope, you should not touch the coarse focus knob. This knob is used to adjust the focus at lower magnifications and can cause the objective lens to crash into the slide if used at high power, potentially damaging the slide or the lens.
The coarse adjustment knob should never be used when viewing in high power with a compound microscope. When in high power, use the coarse adjustment (the knob smaller than the coarse adj.) to more accurately focus on the subject.
You would use the coarse focus knob to focus on low power. Turn the coarse focus knob clockwise to bring the specimen into view and then fine-tune using the fine focus knob.
The coarse focus knob should be used with the low power objective but not with the high power objective. The point of using the coarse focus knob is to bring the specimen into general focus before fine-tuning with the high power objective, which requires more precise adjustments.
First focus the microscope on the lowest objective using first the coarse djustment knob and then the fine adjustment knob. Once you have it in focus, move on and do the same for the next highest objective. Continue this process until you reach the highest objective and focus it in the same fashion.
The coarse focus knob should be used with low power objective lenses, typically 4x and 10x, to bring the specimen into general focus quickly. This knob makes larger adjustments to the focus position.
When focusing the object under low power, you should use the coarse focus knob first to bring the object into general focus. Once the object is roughly in focus, then you can use the fine focus knob to sharpen the image.
You do not use the coarse focus knob on high power because it can damage the slide and the objective lens of the microscope. Use only the fine focus knob to bring the specimen into sharp focus on high power.
The fine adjustment knob is typically used to focus when using high power magnification on a microscope. It allows for precision adjustments to fine-tune the focus of the specimen being observed.
The depth of field is so small that a very small vertical travel could shift the focus from the top of the specimen to the bottom. A very fine adjustment must be used, which is why the coarse adjustment screw is implemented.
The adjustment knob that moves the body tube for focusing with the high-power objective lens is called the fine focus adjustment knob. It allows for precise adjustments to bring the specimen into sharp focus at high magnifications.
The coarse focus adjustment knob is used to move the objective lens closer to or further away from the specimen in large increments, allowing for quick focusing at a general level. This adjustment is typically used initially to bring the specimen into view before fine-tuning the focus with the fine focus knob.
When using the scanner and low objective on a microscope, you should use the coarse focus knob to bring the specimen into approximate focus and then use the fine focus knob to achieve a sharp image. Adjusting the height of the stage may also be necessary to fine-tune the focus.