Methods to determine the size of an object in microns
From OpenWetWare
=Mathematically
Pixels on our CCD are 6.45um.
The size (in microns) of one pixel in an image will depend on how much the image was magnified before reaching the CCD:
[math]\displaystyle{ \mbox{Pixel size} = \frac{6.45um}{total magnification} }[/math]