why use a course focus knob

The coarse focus knob is the knob which moves the microscope stage a larger distance per rotation. The purpose of this knob is to get roughly close to the correct focus on the specimen. Usually, you use the coarse focus knob first and then improve the focus more by reverting to the fine focus knob.

Full Answer

What does the coarse focus knob do?

Because the coarse focus knob moves the stage a larger distance per rotation, it can be hard to perfect the focus with that knob. You’ll move it a tiny bit and you might jump over the best focus.

Can I use the course focus knob on the light microscope?

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.

What is fine focus adjustment knob used for?

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. Home Study Guides Science Math and Arithmetic History Literature and Language

Which focus knob should I use with my camera?

Second, only use the fine focus knob from 10x and up. The coarse focus knob is good for getting an approximation of focus when using the red striped 4x scanning lens. But above this, I recommend using fine focus to minimize the chances of a big hit between the stage and lens. (Still be careful – there are no guarantees here!)

Why is the coarse focus knob important?

Focus (coarse), The coarse focus knob is used to bring the specimen into approximate or near focus. Focus (fine), Use the fine focus knob to sharpen the focus quality of the image after it has been brought into focus with the coarse focus knob.

On which objectives should you use the coarse adjustment focus knob?

The coarse focus knob should only be used with the 4x low power objective in place. The fine focus know can be used with all objectives, including the 4x, but the effect will not be visible with this latter one (you will have to turn the knob many times, which is inconvenient).

When using the coarse focus knob How Should You Be view the slide explain why?

Viewing Prepared Slides On LOW POWER ONLY, use the coarse focus knob to get the object into focus. If you cannot see anything, move the slide slightly while viewing and focusing. If nothing appears, reduce the light and repeat step 4. Once in focus on low power, center the object of interest by moving the slide.

What are the benefits of focusing properly?

Benefits of being focusedBuilds momentum. When you stay focused on one assignment, you're more apt to complete it with greater efficiency. ... Increases productivity. ... Reduces stress. ... Produces better quality of work. ... Eliminate distractions. ... Prioritize your tasks. ... Train your mind. ... Work in a quiet space.More items...•

How to protect microscope objectives?

There are two main ways you can protect your objectives when in use. First, ensure you get spring loaded lenses.

Where is the tension adjuster on a microscope?

Some microscopes have a tension adjuster located behind the coarse focus knob. This is something I rarely touch, but if you notice the adjustment knobs are too stiff or loose, you can adjust the tension with the adjuster. You may notice sometimes that the stage will start to fall from its set position.

How to tell if a lens is spring loaded?

Some don’t have the marking – but you can tell it’s spring loaded by simply pushing on the end and seeing if it retracts. Spring loaded lenses will retract when they hit up against the stage or specimen to protect the lens from damage. Second, only use the fine focus knob from 10x and up.

What is the coarse focus knob used for?

But the coarse focus is also useful for pulling the stage right down for changing specimens and moving the stage to remove the condenser that sits under the stage.

What is a stage stop?

The stage stop is a tool that will help you remember a stage position. Raise the stage to a position that has good focus for your specimen, then flick the stage stop on. Then, you can lower the stage to adjust the slide or swap slides, then raise the stage again.

Where is the focus knob on a microscope?

2. Where to Find the Focus Knob on a Microscope. The focus knobs on a microscope are located at the base of the arm of the microscope, behind the stage.

What happens if you focus high power objectives with the coarse focus knob?

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.

Why is 4x objective better than 4x objective?

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.

Where are the Coarse Adjustment and Fine Adjustment Knobs?

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.

Which One Should I Use

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.

Which Way Do I Turn the Knob?

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.

How to Adjust Tension

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.

Takeaways

Knowing the difference between fine adjustment and coarse adjustment knobs on the microscope is an integral part of focusing the microscope.