The microscopic object is very tiny and we can not see that with our naked eyes. But how can we calculate the cell size which we have looked under the microscope?
It may be spore and pollen or acritarchs, red blood cell or onion skin’s cell.
Let’s start we an example
At first, calculate the FOV of the microscope. The total diameter of the field of view of the microscope. we can use a scale to measure the Feild of view (FOV).
Suppose it is 0.25 mm in total diameter. Then, If we convert this size in micrometer then it will be 250 micrometers. Now suppose we have found 12 cell or object across this diameter (250 Micrometer) then we can say each cell size is 250 micrometer/12= 20.83 Micrometer.
How can we calculate the cell size if we took a photo of that specific cell under the DSLR Camera mounted above the microscope?
Let’s do it.
Suppose we have counted 12 cell under the FOV of the microscope and if we do full zoom-in of the camera then we can find only some cell under the camera display. Because the camera is now full zoom-in position, so we can not find all the 12 cell as we saw under the microscope. Please note that. to measure the cell size under the microscope we have to do the full zoom for every sample to be the accurate size to measure.
Suppose we found 4 cell under the camera display that means, under the FOV of the microscope we found 4 times higher cell’s in number than that of the cells of Camera display. This number depends on the FOV length and the number of the cell under that FOV.
Another example is that if we found, only one big cell in the camera display then we could found 4 big cells in a FOV that is 250 micrometers/ 4 = 62.5 Micrometer size each cell.
And the same big size cell we can count through the camera display. and that is 62.5 micrometer. It was only one in the camera display and the cell’s in camera the display is 4 times less that FOV. So the camera display size also the 62.5 micrometers.
If you already look some microscope photo by the DSLR camera and observing that image you can count the cell size.
Video demonstration here.