Brunson 771 - Page 33

29 Operation and Adjustment Manual
Neverputthemicrometer
onthetelescopewithout
securingitusingthe
knurledthumbscrew.
Morethanoncewehave
repairedmicrometersthat
haveflownofftheendof
telescopebarrels!
overthecenterofthetarget,andtheimagewillonceagainlooklike
Figure3.12.Youcanthenreadthegraduateddrumonthemi‐
crometertoseehowfaryoumovedthelineofsight.Let’ssaythat
thedrumnowreads0.080”insteadofzero.Thisofcoursemeans
thatthetargetmoved0.080”totherightandthatyouhaveoffset
thelineofsightlaterallytotherightby0.080”tocompensateforthe
targetmovement.
Youcanalsoseefromthisillustrationthatifyouhadestablisheda
referencelinewiththetransit,basedforexampleonimportantma‐
chineparametersorcenterlines,andthenobservedatargetthatwas
supposedtobeinlinewiththeseimportantmachinefeatures,you
couldusethemicrometertomeasurethattarget’sdistanceaway
fromthereferenceline.
Your76‐RH190comesequippedwithanopticalmicrometerwhich
readsinEnglishormetricunits.Variousmicrometersareavail‐
able—somehaveasmallerrange,someabiggerrange,andsome
readintwodirections(horizontalandvertic al)atthesametime.
Themicrometeriseasilymountedonyourtelescope.
Thereisasmallknurledlockingthumbscrewonthemi‐
crometerwhichmaybeloosenedortightenedbyhand.
Thetelescopebarrelhasapinwhichfitsintooneoffour
détente
positionsonthemicrometer.Carefullyputthe
micrometerovertheobjectiveendofyourtelescope(it’sa
closefit)andseatitagainstthestopedge,withthepinon
thetelescopebarrelsituatedinoneofthefourdétentepo‐
sitionsonthemicrometer.Ityouwishtomeasure
hori‐
zontally(sothattheverticalwireappearstomoveleftand
right)thenmountthemicrometersothatthetopofthe
graduateddrumisfacingupordown.Usuallythe
graduateddrumismountedonthesamesideofthetele‐
scopeasthefocusknob,butthiscanbeamatterofper‐
sonalpreference.
Figure 3.12
Figure 3.13
CAUTION:Whenthemicrometer
drumisontheleftorrightsideof
thetelescope,orifyouareusinga
dualaxismicrometer,thetelescope
willnotrotatethroughthestan‐
dardswithoutcausingacollision
betweenthestandardsandthemi‐
crometer.Whenusingthemi‐
crometerinthis
position,youmay
reversethedirectionofthetelescope
whenneededbyrotatingtheeye‐
piece,ratherthanthemicrometer,
throughthestandards.