Ocular or eyepiece lens

lower or objective lens

Usually there are three powers of objective lens

You can turn the objective lens from Low power to higher power.

The coarse adjustment knob is used only with the lowest power objective lens. This is because with the highest objective lens you only use the fine Focus, the coarse focus puts the objective lens too near your slide and can break or scratch your slide.

You can tell which objective lens is in the viewing position, by looking.

Never allow an objective lens to touch the slide, slides are valuable and the upmost care must be taken with them.

the slide may be stained and the stain will get on the objective lens, and then you will have to stop looking and clean the lens.

Caution, do not ever use a rag or paper towel to touch any of the lens. Use only a lens paper, such as the type you use with eyeglasses.

Handle the microscope with the right hand on the handle and the left hand under the microscope.

I had one professor who told the class that when we carried the microscopes to the table to use, that if we fell we were to roll over on our back with the microscope still in our outstreighed hands.

i think its 2 or 3 or 4 idk i dont pay atention to buisy talking lol

but its not supost to be to touch the slide cuz it might scratch it ,and it mite get stuck the water or watever ur looking at,and it will get the lens dirty,trust me ,i acidentally did that with some nasty green water >:]