Important Microscope Techniques Field of view the area you can see on the slide as magnification increases field of view decreases Depth of field thickness of the zone that is in focus. as magnification increases depth of field decreases

What happens to the field of view as magnification increases?

Example of Depth of Field                                                                 Euastrum verrucosum

Brightness decreases Orientation as magnification increases, brightness decreases Orientation position of the image compound microscopes flips image upside down and left to right

Working Distance objective lens and the area in focus the distance between the tip of the objective lens and the area in focus as magnification increases, working distance decreases!

Focusing At low power, use coarse adjustment first, then use fine adjustment Focus at low before switching to high power because: 1. object will be in approximate focus at high 2. you won’t hit high power lens on slide At high power never use coarse adjustment because: you could damage objective or slide Use fine adjustment at high power to see different levels within the same cell

Centering to center an object, move the slide: in the opposite direction that you want the image to move in always center at low before switching to high power because: -if you don’t the object will not be within high power field of view

In order to center this object, in what direction should you move the slide?

Preparing a “wet mount” slide Place a drop or two of water on empty slide Add cells you want to look at Add some more water Cover cells with a “cover slip” To avoid trapping air bubbles…. add cover slip at 45 degree angle, then slowly lower the upper edge

Wet Mount Image What do you notice about the angle? Why is this important?

Eyepiece – Magnifies the image. Part that you look through. Body Tube – Refracts (directs) light towards the eyepiece. Coarse Adjustment Knob – Moves the stage, allowing the image to focus. Fine Adjustment Knob – Changes depth of field (near sighted vs. far sighted), makes image sharper Arm – Supports the upper pieces of the microscope Base – Supports the entire microscope Light Source – Provides light to make specimen visible Diaphragm – Filters the light (either amount of light or color) Stage – Platform that holds the slide Stage Clips – Keeps the slide in place Low Power Objective Lens – Magnifies the image High Power Objective Lens – Greatly magnifies the image Nosepiece – Rotates the Objective lens, allowing you to switch between high and low power Slide – Glass that contains specimen. It is placed on the stage so that light passes through it

Magnification When trying to figure out what magnification you are currently viewing the slide at, multiply the magnification of the Eyepiece by the magnification of the objective lens. Ex: If the Eyepiece magnifies the image by 10x, the low power objective lens magnifies it by 4x, and the high power magnifies it by 10x… -The total magnification under low power would be 40x -The total magnification under high power would be 100x