Focus Micoscope
A look at what is currently available on eBay
 Hand Held 60X to 100X Manual Focus Micoscope Magnifier Black US $11.40 
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 Hand Held 60X to 100X Manual Focus Micoscope Magnifier US $9.35
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 Hand Held 60X to 100X Manual Focus Micoscope Magnifier US $12.43
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 Hand Held 60X to 100X Manual Focus Micoscope Magnifier Black US $11.40
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 Hand Held 60X to 100X Manual Focus Micoscope Magnifier US $9.30
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 Hand Held 60X to 100X Manual Focus Micoscope Magnifier US $9.63
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what do these parts of the micoscope do?
barrel
objective lens
coarse focus knob
fine focuc knob
Barrel or eyepiece of a microscope:
the lens at the top that you look through. They are usually 10X or 15X power.
Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X. To have good resolution at 1000X, you will need a relatively sophisticated microscope with an Abbe condenser. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are color coded and if built to DIN standards are interchangeable between microscopes. The high power objective lenses are retractable (i.e. 40XR). This means that if they hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide. All quality microscopes have achromatic, parcentered, parfocal lenses.
The coarse focus knob moves the tube and lenses closer and farther away from the specimen. It is used to focus. Some microscopes only have a coarse focus knob, but many also have a fine focus knob which does the same thing as the coarse focus knob, but moves the tube and lenses less.
The fine adjustment of a compound microscope could move the body tube down or the stage up in tiny distances to help you focus in HIGH power.
