3.5: Field of View
- Page ID
- 124525
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Field of View
The field of view (FOV) is the actual “circle” seen when looking through the lens of the microscope. The diameter of this circle decreases as magnification increases.
The diameter of the field of view (FOV diameter) can be used to get an estimate of the size of the specimen you are viewing.
Procedure for finding FOV diameter
- Place a clear plastic ruler on the stage of the microscope over the opening in the middle of the stage.
- Use the metric side of the ruler, focus on the lines of the ruler with the scanning objective in place. Place a line exactly at the edge of the FOV.
- Measure the diameter of the scanning objective field of view by counting the number of lines that are visible at the diameter of the field of view.
The distance between each line is 1mm. Record the measurement below. Since cells are microscopic structures, they are usually measured in micrometers (μm).
1mm = 1000μm.- Scanning Objective FOV Diameter = _______________________mm * 1000 = _______________________μm (use the μm value for your upcoming calculations!).
- To measure the FOV diameter at a different objective power, use the following formula:
Questions on finding FOV diameter
- Using the formula shown above, find the low power objective FOV diameter of the microscope (this is your UNKNOWN). Make sure to use the Scanning Objective FOV diameter that you calculated from Part 3.1 of the Procedure section above. The Scanning Objective FOV diameter that you found will be your "Known FOV Diameter" value in the formula.:
- Using the formula shown above, find the high power objective FOV diameter of the microscope (this is your UNKNOWN). Make sure to use the Scanning Objective FOV diameter that you calculated from Part 3.1 of the Procedure section above. The Scanning Objective FOV diameter that you found will be your "Known FOV Diameter" value in the formula.:
Finding length of a cell using FOV diameter
Once the FOV diameter for each objective lens is determined, it can be used to estimate the size of the specimen. See the example below in Figure 11.
Figure \(\PageIndex{1}\) Estimating the length of a cell using FOV diameter. (Image credit: Estimating Cell Size by Harmony Folse licensed under CC BY-SA 4.0)
- To estimate the length of the specimen (Figure \(\PageIndex{1}\)), estimate how many specimens will fit across the FOV horizontally. If 4 fit across the FOV, the length is:
Practice Calculating Length of a Cell using FOV diameter
- If the FOV is 600μm and 30 cells can fit across the FOV horizontally, what is the length of the cell? Show your calculations below.