The total magnification and the diameter of the field of vision have an inverse relationship; that is, as magnification rises, the diameter of the field falls in proportion, hence the diameter of the field of view at different magnifications may be computed quantitatively using the formula. D = 1/m × d where m is the magnification, D is the diameter of the field of view and d is the diameter of a single frame of film or photo. For example, if you can see to the distance of 10 feet at 100 yards away then the magnification is 10:1 so the diameter of the field of view is 10 feet or 0.3048 meters.
Therefore, the magnification of a lens system has an inverse relationship with the field size it will render visible. That is, as the magnification increases so does the diminution of the field of view.
For example, if you could see to the distance of 10 feet at 5 miles away then the magnification would be 20:1 so the diameter of the field of view would be 20 feet or 6.096 meters.
As another example, if you could see to the distance of 1 foot at 40 miles away then the magnification would be 500:1 so the diameter of the field of view would be 0.0384 inches or 9.5225 millimeters.
The magnification of the objective lens has an inverse relationship with the field of vision. For example, if your field of vision diameter is 1.78 millimeters at 10x magnification, a 40x objective will be one-fourth as broad, or around 0.45 millimeters. The field of view of this microscope would be about 0.1 square millimeter.
For general use, a 100x objective lens is suitable for viewing small objects such as bacteria, pollen, dust, etc. While you can see finer details using higher power objectives (400x and above), most biological samples are not well suited to high magnifications because they become too fragile.
In conclusion, the larger the object being viewed, the smaller the corresponding objective lens should be. This is true whether you are using microscopy to examine large organisms like plants and animals, or small ones like bacteria and viruses. Objectives range in price from less than $100 for low power lenses up to several thousand dollars for high power models.
What exactly is the field of view? The diameter of the field of view shrinks as magnification rises. In other words, as the magnification increases, you can see less of the specimen. There's no way around this; it's just a fact of life. However, you can adjust where in the specimen this effect occurs by using different objectives.
For example, if you were to use a 10-power objective on a microscope, you would be able to see ten times more of the specimen than if you used a 2-power objective. Because higher powers reveal more detail, they show you a wider range of magnifications over which to work. Lower powers are useful for looking at large areas of tissue or for obtaining wide views of the sample.
Generally, the larger the object being viewed, the lower the power should be. Small objects can often be better seen with high powers.
So, increasing magnification allows you to see smaller structures within the sample. But, you need to remember that you're seeing less overall so you won't be able to examine anything beyond what's directly under the lens.
Furthermore, objects far away from the center of the frame will appear blurry due to diffraction effects. These effects become significant when viewing small objects at high powers.
Simply multiply the ocular lens (10x) by the objective lens to get magnification. You may get four different magnifications with this microscope: 40x, 100x, 400x, and 1000x. A clear mm ruler was used to measure the original dimensions of the field of vision (fov). Then, the f-number was calculated by dividing the size of the fov divided by the size of the hole in the lens that lets light in.
For example, if we look at a field of view that is 1/8th of an inch wide and measure 200 feet away from it, then we can calculate the magnification by multiplying 0.125 x 10 = 1.50. The camera can only record an image that fits inside its sensor, so the maximum magnification it can display is 1:1. However, many scientific instruments are able to display magnifications up to 500x or more because they use electron microscopy sensors that are much larger than the charge-coupled devices in regular cameras.
Here are two other examples using the same field of view: If the microscope is set to 40x, then the fov will be 1/40th of an inch wide and 200 feet away from it we would estimate the magnification to be 40x. If the microscope is set to 100x, then the fov will be 1/100th of an inch wide and 200 feet away from it we would estimate the magnification to be 100x.
Your magnification level will directly address the operating distance and field of vision of your magnifier. A 5x magnification, for example, represents a field of vision of 1.5". You can adjust the viewing distance using the arm or stand provided with your reader.
The smaller the field of view, the greater the magnifying power. For example, if you decide that your field of view is 2.5 mm in diameter with a 10X ocular and a 4X objective, you may use the above calculation to calculate what your field of view will be with the high power objective. It will be 20 microns or 0.02 mm across.
For most applications, a 100-micron (0.01mm) field of view is sufficient for viewing single bacteria. A 500-micron field of view would allow you to see several bacteria simultaneously without overlapping. A 1-millimeter field of view would show the entire slide.
When you increase the magnification of the microscope beyond 10X, the field of view becomes relatively small. At 40X magnification, you can cover about 50 microns with one field of view. This means that if you wanted to view multiple cells on one section of a slide, you would have to stack them together or use multiple sections.
There are two ways to increase the size of the field of view: use a higher numerical aperture lens or step up from conventional microscopy to scanning electron microscopy (SEM). Both methods are discussed below.