5 brightfield microscopy

Why should the fine focus knob typically be used with the 10X and 40X objective lenses?

The slide should be close to in focus after focusing at the 4X objective. Focusing with the coarse focus knob would result in too large a change in focus.

True/false: The goal of microscopy is to create a magnified image of objects too small to be seen with the eye alone.

True

True/false: When focusing on a slide, start on the scanning, or low power, objective lens.

True

The _______________ is the amount of the slide you are able to see through the eyepiece.

field of view

Additional adjustments to the microscope can be made regarding __________.

lightning

________________ is the apparent increase in image size

magnification

There are three factors that determine the quality of a microscopic image:

magnification, resolution, contrast

______________ is the ability to distinguish fine detail.

resolution

Often what you want to visualize is not in the middle of the field of view and you must move the slide around to find what you want to study. To move the slide, you move the __________.

stage

________________ is the overall enlargement of the image of a specimen. To calculate total magnification, multiply the magnification of the ocular lens (10X) with the magnification of the objective lens.

total magnification

In this phase, you will take all the steps necessary to focus on a cell indicated with a yellow star using the slide provided and magnifying all the way up to the 40X objective.Complete the following steps:

1. Click power switch to turn on light 2. Adjust light to appropriate brightness 3. Focus at 4X using coarse focus knob 4. Adjust ocular lenses to view one image 5. Focus using fine focus knob 6. Adjust the stage to move the star to the center of microscope view 7. Put 10X objective in place 8. Focus using fine focus knob 9. Put 40X objective in place 10. Adjust using fine focus knob

The microscope you are using has four objective lenses to magnify the image: ____X, ____X, ____X, and _____X.

4,10,40,100

What is the total magnification of a specimen using the 40X objective?

400X

T/F; The higher the power objective, the greater the field of view.

F

As magnification of the image increases, the light intensity ___________ and will have to be adjusted.

decreases

What is the advantage of starting with the 4X objective before moving to the 10X and then the 40X objective?

The field of view is larger, and it is easier to focus.

How do the coarse and fine focus knobs work on a brightfield microscope?

The focus knobs move the stage up and down.

The sliding bar on the condenser lens is the ____________. As you move the _____________ to decrease the light to the slide, the contrast ___________. As you move the _____________ to increase the light to the slide, the contrast ____________.

aperture, increase, decrease

depth of focus/field

as the magnification increases the depth of focus decreases

Microscopes are often used to study _______, __________ and __________.

bacteria, cells, tissues

Brightfield microscopes use a _____________ of glass lenses and light to view the specimen.

combination

The _____________ focuses the light on the slide

condenser lens

Which of the three factors affecting image quality is altered by the light source?

contrast

___________ refers to the ability to distinguish objects, such as cells, from the background.

contrast

Fields of study where a microscope is a necessary tool include (3)

cytology: the study of cells histology: the study of tissues pathology: the study of disease