Coverslips are very thin sheets of glass with straight, clean edges - treat them as if they were 4-sided razoerblades. If you drop one onto the table or floor, do not try to wrestle it up off the surface by the edges - if they don't come up easily, slide them to the edge of the table or use a piece of tape to pick it up, then throw it into the sharps disposal.

Be sure all used slides and coverslips go to into the sharps disposal.

Carry microscopes carefully and with both hands. Make sure the turret isn't loose - if overloosened, these can fall off, usually resulting in their destruction, and these are very expensive.

Near one end of a slide, place a drop of sample. If the sample is dry (e.g. part of a colony), use water, then add the sample to this drop, and mix just a little. You should be able to see things in the droplet - if it's perfectly clear and clean-looking water, try again.

Drag a coverslip over the droplet until to touches the underside of it, then drop the coverslip onto the drop.

If the size of the droplet is just right, the liquid will fill all of the space beneath the coverslip without floating or oozing out the side. If it does ooze out, use the edge of a paper towel or Kimwipe to draw out the excess. Too much liquid not only makes a mess, but gives too deep a field (you won't be able to focus all the way to the botttom of the sample) and attempts to focus will only move the coverslip up and down, pumping the sample in and out of the field of view. If the liquid doesn't fill much o fthe space under the coverslip, use the back end of a loop to gently push the coverslip down. If it doesn't help, add a drop of liquid to the edge of the coverslip and let it be drawn in. Not enough liquid is also a problem; the sample may be too dense, or there may be a hard obstruction, holding the coverslip up. Even if not, capillary force will pull the coverslip very tightly down onto the slide, crushing anything delicate in the sample. Don't worry - with practice, you'll soon be getting it right every time.

The microscopes we use in this class are the same Nikon's you used in General Microbiology (assuming you had MB 352M or H) and in Medical Micro lab (MB 412), and so they should be familiar.

There are 2 objectives on these microscopes (10X bright field and 100X phase-contrast oil-immersion), and 2 condenser setting (bright field or phase contrast); there are therefore 4 possible types of microscopy possible:

Remember that the occulars provide an additional 10X magnification over that of the objective.

The objectives are distinguishable by color and size - the 10X objective is smaller and labeled in yellow, the 100X objective is larger and green. These rotate into place - remember that you need oil for the 100X objective, and cannot have oil in place for the 10X objective.

The condenser (under the stage) has a slider - to change between "circle" and "ring", push this slider all the way left or right. The side labeled "Ph3" is the phase ring setting - because this lets only a hollow cone of light through, you will see an obvious decrease in the amount of light on the sample.

1. Make a wet mount from the samples provided by the instructor, and load it onto the stage of your microscope.
2. Make sure the condenser is set to "circle" (bright field). Swing the 10X bright objective into place, and crank the focus all the way up.
3. Adjust the fine focus down until the image appears.
4. Now look around, have fun! Try changing the condenser to phase-contrast ("ring") for a dark field view - this is often a good way to scan a sample. When you find something small you want to look closer at, center that object as best you can in the field of view, swing the 10X objective out of the way and add a drop of oil to the coverslip, and swing the 100X objective into place. You will need to refocus, but only a bit, no more than 1 turn of the fine focus either way.
5. Clean all oil and sample from your microscope using Kimwipes, cover, and put back into the microscope cabinets.

"Why can't I see anything?"

• Is the condenser all the way up?
• Is the iris on the condenser open?
• Is there oil between the objective and the coverslip?
• Do you have two coverslips instead of one? (This is easier to do than you'd think.)
• Are both objectives tight?
• Is the light on?
• Is the turret tight?
• Is the objective miles away from the slide?
• Is the objective properly aligned?
• Is the slider all the way right or left?
• Are the objective, condenser, and/or occular dirty?
• Are you focused on dust on the bottom of the slide, or the top of the coverslip, instead of your sample?
• Do you actually have anything in your sample?