Microscope Step-By-Step



If using a prepared slide, inspect it by eye (find the specimen if possible) and clean it off.


If preparing your own slide, clean it and dry it, then put your specimen and, if necessary, a drop of water (wet mount) on the slide.  If you plan to look at a wet mount at the higher powers, you must put a clean cover slip on it.


Start with the low or scanning power (4X) objective lens in position and open the iris diaphragm.  Open the slide clip on the stage, slide the slide into the back opposite corner so it is flat and oriented horizontally on the stage.  Close the clip gently.  Use the slide movement cranks to move the slide until the specimen is in the "spotlight" from below.


Looking through, adjust the dimmer so that the light isn't uncomfortably bright, but don't dim it into the yellow range.  Adjust the iris diaphragm so some contrast is visible in the image.  Focus, course adjustment knob first, with the non-adjusting eyepiece (only use that eye), on some particular detail.  Fine focus with the fine adjustment knob.  Using the other, adjusting eyepiece, and using that eye only, focus on the detail for that eye.  Adjust the distance between the eyepieces so both eyes can see that detail together as one image (be patient).  Look to see that the condenser lens is up close to your slide but not passing on an image of the light source surface.


Look around your specimen.  You'll find things much more quickly at the lower powers - don't move up until you have something to look at.  If you aren�t sure of the focus, focus on the edge of the cover slip or edge of the water droplet and then scan.  Before going up in power, center a clearly-visible detail.  When changing powers, make sure the lens clicks into place.  When putting either of the higher power objective lenses in place, lean back and watch to see if it's going to hit your cover slip - if you're worried that it will, call for help.  Do NOT separate the parts, move to high, and then move them back together.


Once on the higher powers, focus with the fine adjustment knob only!!!


If working at 100X - oil immersion - make certain you have something at 400X before you go up.  Move the 40X lens out of the way, put a drop of immersion oil on your cover slip, and move the 100X lens into the oil.  You can not go back to 40X with that oil there!  Make sure you clean both the lens and the slide of oil when you are done.


When finished, take your slide off the 'scope.  Put the low power objective in place.  Unplug and loosely coil the power cord, then hang it on the oculars.  Cover the 'scope and place it in the cabinet so that the next person can easily slide it out.


DIRT PROBLEMS.  Lenses are to be cleaned with lens paper!   If dirt is only visible to one eye, spin the eyepiece -if the spots spin, clean the eyepiece.  If spots move with the slide, clean the slide.  If field is hazy, clean the objective lens.  Dirt is rarely on the condenser or light source - it might actually be on (or in) your eye, especially if you're using only one.




First Written 1990;  Last Update 2000;  Web Version 2001,  M. McDarby




Hit Counter