# Methods to determine the size of an object in microns

### 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:

$\mbox{Pixel size} = \frac{6.45um}{\mbox{total magnification}}$

Assuming that the magnifier is at position 1x (not 1.5x), this formula gives us:

• 60x  : 0.1075 um/pixel or 9.30 pixels/um
• 40x  : 0.1613 um/pixel or 6.21 pixels/um
• 20x  : 0.3225 um/pixel or 3.10 pixels/um
• 10x  : 0.645 um/pixel or 1.55 pixel/um