What is the effective displayed magnification on my screen using the Digital Microscope Imager (DMI) #44421?

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	What is the effective displayed magnification on my screen using the Digital Microscope Imager (DMI) #44421?

Answer Celestron’s DMI has no internal lenses (the manual’s statement of a 15x built-in lens is incorrect). So the magnification you get with the camera depends just on the microscope objective you are using and on properties of the camera’s chip and your computer’s screen.

The properties needed are:
(1) the camera chip is approximately 5mm x 3.75mm.
(2) The camera resolution is 1600x1200 pixels.
(3) Typical computer screens display at 100 percent at 75 pixels per inch or a display resolution of 3 pixels per millimeter (mm). This can vary depending on a number of factors set by the computer monitor or graphics.

For this worked example, the DMI is used in a stereo microscope with a 2x objective. First, how big is the specimen image and second, how much magnification will be displayed on the screen at normal (100 percent) view?

The actual size of the specimen (width or height – here we choose width) optically imaged on the chip is determined by the chip size divided by the objective magnification. That is 5mm divided by 2x or 5/2 = 2.5mm. So a 2.5mm specimen will cover the whole 5mm camera chip of the DMI with this objective. (As you’d expect, higher-power objectives will give even more optical magnification.)

The very small optical image will be greatly enlarged because of the high resolution size (in pixels) of the chip compared to the display resolution (pixels per millimeter). This factor is 1600/3 or about 533 for the DMI and a typical monitor.

The displayed magnification is this factor divided by the image size. For the stereo microscope with the DMI and 2x objective, the effective displayed (screen) magnification is thus 533/2.5 = 213 times.

Article Details

Article ID:

2358

Created On:

Mar 23 2010 02:30 PM