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.
Fine adjustment knobs are the smaller knobs and are also used to raise and lower the stage but more slowly and in a more controlled manner under higher magnifications. In this article we will discuss when it is appropriate to use each, and where they are located on the microscope.
The coarse adjustment knob is responsible for finding the image on the stage and getting the image quickly into focus. The fine adjustment knob then keeps the specimen in focus while the user views it under different magnification levels.
There are several reasons why you should use the coarse focus knob only with the 4x objective and not with the high power objectives. Reason 1: protect the objectives from damage 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.
Low Power Objective (10x) The low power objective lens has more magnification power than the scanning objective lens, and it is one of the most helpful lenses when it comes to observing and analyzing glass slide samples. The total magnification of a low power objective lens combined with a 10x eyepiece lens is 100x magnification, ...
NEVER USE THE COARSE FOCUS KNOB ON HIGH POWER! The high power lens should be very close to your slide when in proper focus. If you turn the coarse adjustment knob while on high power, the objective could easily break your slide.
Coarse and fine adjustment The coarse adjustment knob should only be used with the lowest power objective lens. Once it is in focus, you will only need to use the fine focus. Using the coarse focus with higher lenses may result in crashing the lens into the slide. 6.
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.
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).
the coarse focus knobs? A: Only use the fine focus with the 40X and 100X objectives; can use the coarse focus with the 4X and 10X objectives.
Use the coarse adjustment knob when you have a greater working distance. Only use the coarse adjustment knob on 4x or 10x objectives, not on the 40x or 100x objectives.
Why should the fine focus knob typically be used with the 10x and 40x objective lenses? The slide should be close to in focus after focusing at the 4X objective. Focusing with the course focus knob would result in too large a change in focus.
400xMagnificationTotal MagnificationScanning4x40xLow Power10x100xHigh Power40x400xOil Immersion100x1000xAug 1, 2021
The light intensity decreases as magnification increases. There is a fixed amount of light per area, and when you increase the magnification of an area, you look at a smaller area. So you see less light, and the image appears dimmer. Image brightness is inversely proportional to the magnification squared.
You might need to readjust the sample into focus and/or readjust the condenser and light intensity. If you cannot focus on your specimen, repeat steps 3 through 5 with the higher power objective lens in place. Do not let the objective lens touch the slide!
For example, a wet mount slide must be incredibly secure in order to use immersion oil with it. If switching between a dry 40x lens and a 100x oil lens, care must be taken not to get oil on the 40x lens, which could damage it.
0:092:45How to Focus a Microscope & How the Field of View Changes - YouTubeYouTubeStart of suggested clipEnd of suggested clipBegin by turning your microscope on and adjusting the light intensity to about five or six thenMoreBegin by turning your microscope on and adjusting the light intensity to about five or six then place your slide in the clamp on the stage. And center the specimen over the condenser.
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.
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.
Some better microscopes have a focus lock lever. This lever blocks the stage at the pre-determined position. You set up the focus starting at 4xy and work your way up to 100x oil. You then engage the lever and the position will be remembered. You can then use the coarse focus to lower the stage, insert a new slide, and without changing the objective use the coarse focus (!) to raise it up again until the stage blocks (this position was remembered). This is an efficient method that allows you to quickly observe one slide at high magnification after another. Why not just change the slide by pulling it out horizontally? The reason is that if there is immersion oil on the slide, then objective should be lowered into the oil from the top and not from the side, to prevent smearing of the immersion oil all over the place.
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.
Use the coarse focus to raise the stage all the way up until it blocks. The objective at the highest position, the 4x objective should of course not touch the slide.
The coarse focus raises and lowers the stage to quickly, that it is inevitable that you lose the focus when you use high-power objectives. One purpose of focusing is to look at the different layers of a specimen. By turning the fine focus, you can “section” through the specimen. The coarse focus does not allow you to do this.
The coarse adjustment knob on most microscopes is along the lower middle part of the arm of the microscope as shown in the image below.
The basics of using a microscope tells us that we should start with the lowest power objective first and with the stage at its lowest position.
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.
Some microscopes will come with a tension adjuster. This allows you to manipulate the tension of the adjustment knob to determine how soft or how hard do you have to turn the knob to attain the desired level of movement from each revolution of the knob.
Knowing the difference between fine adjustment and coarse adjustment knobs on the microscope is an integral part of focusing the microscope.
if after focusing in lower power, you need to use only the fine adjustment to focus the specimen at the higher powers
located on base of arm and adjusts the intensity of the light