Question

1. looking from the side, turn the largest coarse focus adjustment knob until the stage and objective lens are as close as possible.
2. while looking through the ocular lenses, adjust the coarse focus knob until you are focused on the sample.
3. adjust your light intensity with the diaphragm lever.
4. slowly turn the fine focus adjustment knob to sharpen the focus until you can see your specimen clearly. center the object in the middle of the field of view.

always look from the side when changing objectives to avoid breaking the slide, and never focus the stage upwards toward the objective lens with the coarse focus knob. you might break or scratch the lenses.

1. holding only the revolving nosepiece, rotate the nosepiece to the next objective lens (10x) until it clicks into place.
2. slowly turn the fine focus knob to focus the sample at the new magnification. remember, you do not need to use the coarse focus knob after you find the sample with the lowest (4x) power lens because it should already be almost in focus. you may need to increase the light intensity.
3. repeat steps 9 - 10 when you switch to the 40x objective lens.

with two - lens systems, there is a simple method to figure the total magnification when using each objective. the total magnification is equal to the magnification of the ocular multiplied by the magnification of the objective. for each objective, determine the total magnification and write it in table 5.2. the field of view (fov) diameters are provided in table 5.2.
table 5.2: information on objective lenses.

objective	objective magnification	ocular magnification	total magnification	fov (mm) diameter
low power	10x			1.80
high power	40x			0.45
oil immersion	100x			0.18

Explanation:

Step1: Recall magnification formula

Total magnification = Ocular magnification × Objective magnification

Let's assume the ocular magnification is a constant value \(x\).

For the scanning objective with objective magnification \(4\times\), and total magnification \(M_1\), we have \(M_1 = 4x\). Given \(M_1\) can be calculated from the relationship with FOV. But if we assume a standard ocular magnification of \(10\times\) (common in microscopes)

Step2: Calculate total magnifications

For scanning objective:
If ocular magnification \(= 10\times\) and objective magnification \(=4\times\), then total magnification \(=10\times4 = 40\times\)
For low - power objective:
Objective magnification \( = 10\times\), ocular magnification \(=10\times\), total magnification \(=10\times10=100\times\)
For high - power objective:
Objective magnification \( = 40\times\), ocular magnification \(=10\times\), total magnification \(=10\times40 = 400\times\)
For oil - immersion objective:
Objective magnification \( = 100\times\), ocular magnification \(=10\times\), total magnification \(=10\times100=1000\times\)

Answer:

Objective	Objective Magnification	Ocular Magnification	Total Magnification	FOV (mm) Diameter
Low Power	\(10\times\)	\(10\times\)	\(100\times\)	\(1.80\)
High Power	\(40\times\)	\(10\times\)	\(400\times\)	\(0.45\)
Oil Immersion	\(100\times\)	\(10\times\)	\(1000\times\)	\(0.18\)