APPENDIXF–MICROSCOPES
MicroscopeUse
Themicroscopeisaveryimportanttoolinbiology;itallowsustoseeandstudythingsthat
are impossible to see otherwise, like cells and their contents. Since we are primarily
visually-oriented animals, microscopes are especially important tools for gathering
information. There are two types of microscopes that we will use in the laboratory –
dissectingmicroscopes,andcompoundmicroscopes.Thefollowingrulesapplytotheuseof
bothtypesofmicroscope:
1 – Always carry the microscope with one hand grasping the arm and one hand
supportingthebase,keepingthemicroscopelevel.
2–Neverkeepthelightsourceonthemaximumsettingforanextendedperiodof
time.
3–Neverleavethelightonwhenthemicroscopeisunattended.
4–Neverforceaknoborcontrol.Gethelpfromtheinstructorifsomethingwon’t
move.
5 – Always move from the lowest-power objective to successively higher-power
objectives.
6–Neverunscrewanobjectiveunlessinstructedtodoso.
7–Alwayscleananoil-immersionlensimmediatelyafteruse,andcleananyoilthat
mighthavespilledonthestage.
8–Neverleaveaslideonthestagewhenstoringthemicroscope.
9 – Always put the lowest-power objective back into place for storing the
microscope.
10–Alwayscoverthemicroscopewhenstoringit.
A.DissectingMicroscopes
The dissecting microscope is used when you only need a little magnification, when your
specimenistoolargetoplaceonaslide,orwhenyouwanttoobservethe3-dimensional
surface of an object. Figure F1 shows the different parts of a generalized dissecting
microscope.
Touseadissectingmicroscopeproperly,followthesedirections:
1.Carefullyremovethemicroscopefromthecabinet.Holditinanuprightpositionwiththe
armofthemicroscopeinonehandandsupportthebasewiththeotherhand.Alwaysuse
bothhandswhencarryingamicroscope.
2.Placethemicroscopesecurelyonthelabbench,makingsuretheeyepieces(alsocalled
oculars) and stage are oriented towards yourself. Remove the cover, and plug in the
microscope.
3.Placethespecimenyouwishtoobserveintoacontainer(e.g.aPetridish)beforeputting
itonthestageofthemicroscope.
APPENDIXF–MICROSCOPES
4.Turnontheilluminationusingthepowerswitchesinthefrontofthemicroscope.Note
thatonadissectingscope,youcanilluminatefromabove,beneath,orboth.Most,butnot
allspecimenswillbeeasiesttoviewwithilluminationcomingfromabove.Youshouldtry
differentcombinationstoseewhichprovidesthebestview.
5. Adjust the distance between the eyepieces to match the distance between your eyes –
thismakesiteasiertoseewell.Keepingbotheyesopenwillreduceeyestrain.
6. Turn the magnification knob on the top of the microscope to the lowest power (the
numbersonthedialrepresentthelevelofmagnification).Usethecoarsefocusknobsto
bringthespecimenintofocus.Ifyouwanttoseemoredetail,centertheobjectinthefield
of view, increase the magnification by turning the magnification knob, and refocus as
needed.
7.Afteryouhavefinishedviewingyourspecimen,turnthemagnificationknobbacktothe
lowest power, turn any sources of illumination off, and unplug the microscope. Place the
coverbackonthemicroscope,andusingtwohandstocarryit,returnittoanopenspotin
thecabinet.
APPENDIXF–MICROSCOPES
Figure F1. A dissecting microscope, with labeled parts. Although every model of
microscopeisslightlydifferent,eachwillhavethesemajorcomponents.BasedontheLeica
Zoom2000.
APPENDIXF–MICROSCOPES
B.CompoundMicroscopes
The compound microscope is used when you need a lot of magnification, and your
specimen can fit on a slide. Compound microscopes can vary in the amount of
magnificationtheyprovide,dependingonwhichobjectivesareinstalled.FigureF2shows
thedifferentpartsofageneralizedcompoundmicroscope.
Touseacompoundmicroscopeproperly,followthesedirections:
1.Carefullyremovethemicroscopefromthecabinet.Holditinanuprightpositionwiththe
armofthemicroscopeinonehandandsupportthebasewiththeotherhand.Alwaysuse
bothhandswhencarryingamicroscope.
2.Placethemicroscopesecurelyonthelabbench,makingsuretheeyepieces(alsocalled
oculars) and stage are oriented towards yourself. Remove the cover. Before plugging in
themicroscope,makesurethedimmerswitchisintheOFFposition.
3. Plug in the microscope, and then turn the ON/OFF switch to ON. Rotate the dimmer
switchuntilthelightisbrightenoughforyoutocomfortablylookthroughtheeyepieces.
Donotmovethemicroscopewhilethelampison–thefilamentiseasilydamagedwhenit
ishot.
4. Obtain or prepare the slide that contains the specimen you wish to observe. Handle
preparedslideswithgreatcare.
5.Usethecoarsefocusknobtolowerthestagetoitslowestsetting.Rotatethenosepiece
(also called an objective turret) until the lowest power objective is in place (pointing
towardsthestage).
6.Placetheslideonthestage,andsecureitwiththemetalclasp.Usethemechanicalstage
controlstomovethestageuntiltheregionoftheslideyouwishtoobserveisunderneath
theobjective.(Thelightshouldbeshiningthroughthestageandtheslideatthispoint.)
7.Beforelookingthroughtheeyepiece,turnthecoarsefocusknobuntilthelowestpower
objectiveisasclosetotheslideaspossible,butisnottouching.
8. Adjust the distance between the eyepieces to match the distance between your eyes –
thismakesiteasiertoseewell.Keepingbotheyesopenwillreduceeyestrain.
9. Look through the eyepieces and slowly turn the coarse focus knob until the specimen
comesintofocus.Nowusethefinefocusknobtosharpenthefocus,andthemechanical
stagecontrolstomovethefieldofview,ifneeded.
10.Foroptimallightingandcontrast,firstturnthedimmerswitchallthewayup,andclose
downtheirisdiaphragm.Then,whileviewingthespecimenthroughtheeyepiece,slowly
opentheirisdiaphragmuntilthereisjustenoughlighttoclearlysee.
APPENDIXF–MICROSCOPES
11.Tochangepowers:
a.First,centeryourspecimeninthefieldofview.Makesurethatitisinsharpfocus
atthispower.
b.Rotatethenosepieceuntilthenexthighestpowerobjectiveisinplace(pointing
towardsthestage).
c. Look through the eyepieces again, and use the fine focus knob to sharpen the
focus,ifneeded.Ifyourspecimenhas“vanished”fromview,gobackdowninpower,
re-center,andrefocusbeforegoingbackuptothehigherpoweredobjective.
d.DoNOTusetheobjectivemarked“OIL”unlesstoldtodosobyyourinstructor.
11. After you have finished viewing your specimen, rotate the nosepiece until the lowest
powerobjectiveisinplace,andusethecoarsefocusknobtolowerthestagetoitslowest
setting. Remove the slide from the stage. Turn the dimmer switch OFF, and turn any
sourcesofilluminationoff.Placethecoverbackonthemicroscope,andusingtwohandsto
carryit,returnittoanopenspotinthecabinet.
APPENDIXF–MICROSCOPES
Figure F2. A compound microscope, with labeled parts. Although every model of
microscope is slightly different, each will have these major components. Based on the
NikonEclipsee100.