IV - Microscopes - Determining Field of View
By Kathy Egbert
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Last updated about 6 years ago
16 Questions
Review: You are given a picture of a microorganism and told it is magnified 100 times
(written 100x). Which of the objective lens on your microscope was used to get
this magnification?
Review: You are given a picture of a microorganism and told it is magnified 100 times
(written 100x). Which of the objective lens on your microscope was used to get
this magnification?
Total magnification is calculated by multiplying the ocular lens (10x)
magnification by the magnification of the objective
Review: Even though you have seen this question before, it is essential that you
understand this principle when viewing specimens under the microscope. The
greatest field of view is at what magnification?
Review: Even though you have seen this question before, it is essential that you
understand this principle when viewing specimens under the microscope. The
greatest field of view is at what magnification?
To increase accuracy of measuring specimens under the microscope we use the
micrometer unit of measurement.
To increase accuracy of measuring specimens under the microscope we use the
micrometer unit of measurement.
Practice: Given the measurement 3.25 mm, convert this to micrometers.
Practice: Given the measurement 3.25 mm, convert this to micrometers.
multiply 3.25 mm by 1000
After lining up a millimeter mark on the ruler on one side of the diameter, two
things can happen:
1) the millimeter marks can frame both sides; just count the number of whole
millimeters (look at column 1 below)
2) the millimeter mark frames one side, but not the other (see column 2 below).
Count the whole mm marks first. Now you have to estimate the amount of area that
remains. Does it look like about 1/4, 1/3, 1/2 or ___? Add this fraction to the
whole number. You need to have the fraction in decimal format (1/2=0.5;
1/4=0.25; 1/3=0.33; 1/2=0.5; 2/3=0.66; 3/4=0.75)
After lining up a millimeter mark on the ruler on one side of the diameter, two
things can happen:
1) the millimeter marks can frame both sides; just count the number of whole
millimeters (look at column 1 below)
2) the millimeter mark frames one side, but not the other (see column 2 below).
Count the whole mm marks first. Now you have to estimate the amount of area that
remains. Does it look like about 1/4, 1/3, 1/2 or ___? Add this fraction to the
whole number. You need to have the fraction in decimal format (1/2=0.5;
1/4=0.25; 1/3=0.33; 1/2=0.5; 2/3=0.66; 3/4=0.75)
Figure A measures 4 mm
Figure A measures 4 mm
Figure B measures almost exactly 5 mm
Figure B measures almost exactly 5 mm
Figure C measures 1.3 mm
Figure C measures 1.3 mm
Table 1. Dimensions of the Field of View
Complete Column 1 (a, b, c) by following the instructions in the above slides
and entering measured mm;
Complete Column 2 (d, e, f) convert the mm in column 1 to micrometers by
multiplying by 1000 (this is the diameter);
Column 3 (g, h, i) - to get the radius you divide the diameter by two, this is
"r" in the equation, use 3.14 for pi and complete the multiplication for area
Box X: complete this calculation by taking the low power field of view (Box b)
and dividing it by 4
Box Y: convert diameter in Box X to micrometers
Box Z: use same information for Column 3 above
Table 1. Dimensions of the Field of View
Complete Column 1 (a, b, c) by following the instructions in the above slides
and entering measured mm;
Complete Column 2 (d, e, f) convert the mm in column 1 to micrometers by
multiplying by 1000 (this is the diameter);
Column 3 (g, h, i) - to get the radius you divide the diameter by two, this is
"r" in the equation, use 3.14 for pi and complete the multiplication for area
Box X: complete this calculation by taking the low power field of view (Box b)
and dividing it by 4
Box Y: convert diameter in Box X to micrometers
Box Z: use same information for Column 3 above
Compare the estimated high power FOV area (Box i) with your calculated high
power FOV area (Box z). Which of the following statements best represents your
results
Compare the estimated high power FOV area (Box i) with your calculated high
power FOV area (Box z). Which of the following statements best represents your
results
Based on your answer to Question 10, how would you rate your skills of measuring
the diameter of your FOV?
Based on your answer to Question 10, how would you rate your skills of measuring
the diameter of your FOV?
Prepare a wet mount from a piece of newsprint that has some color on it. Start
with the scanning, 4x objective and bring your specimen into focus. Observe how
the colors are printed onto the wood fibers that make up the newspaper. Using
the information you've just calculated for FOV, estimate the number of colored
dots that are in one square millimeter. Choose just one of the three FOVs to do
this task. Show your work:
Prepare a wet mount from a piece of newsprint that has some color on it. Start
with the scanning, 4x objective and bring your specimen into focus. Observe how
the colors are printed onto the wood fibers that make up the newspaper. Using
the information you've just calculated for FOV, estimate the number of colored
dots that are in one square millimeter. Choose just one of the three FOVs to do
this task. Show your work:
You will now use three different prepared slides from the front table to
practice your skills. Complete a Table for each slide. Specimen #1
You will now use three different prepared slides from the front table to
practice your skills. Complete a Table for each slide. Specimen #1
Repeat with a different slide. Specimen #2
Repeat with a different slide. Specimen #2
Repeat with another different slide. Specimen #3
Repeat with another different slide. Specimen #3
One of those rare opportunities to earn some extra credit. Repeat using a
different slide - Specimen #4
One of those rare opportunities to earn some extra credit. Repeat using a
different slide - Specimen #4