Brunson 771 - Precise Leveling

9 Operation and Adjustment Manual
thumbandforefingeroneachoftwodiagonallyopposedleveling
screws.Tomovethebubble,turnthelevelingscrewsatthesame
time,andinoppositedirections(thumbsmovingtogetheror
thumbsmovingapart).Thebubblewillmoveinthedirectionof
movementofyourleftthumb.Movethebubblesothatitisinthe
middleoftheplatevial,andatleastinlinewiththeinscribedcircle
(itprobablywon’tbeexactlycentered).Nowmoveyourhandsto
theothersetoflevelingscrews.Usingthesameprocess,movethe
bubbledirectlyundertheinscribedcircleinthecenteroftheplate
vial.Youmayhavetorepeatthisentireproc essacoupleoftimesto
getthebubblecentered.Keepalightbutfirmtensiononthescrews
allthetime.Neverputheavytensiononlevelingscrews.
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Nowrotatethetransit180°aboutitsverticalspindle.Thebubble
shouldstaycenteredundertheinscribedcircle.Ifitdoesn’t,the
vialisoutofadjustment(refertoChapter4ofthismanualforthe
calibrationproceduretocorrectthis).
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Topreciselylevel(sometimescalled“precisionplumb”)thetransit
using the coincidence vial, rotate the standards of
the transit until
thetelescopeisinlinewithonepairofdiagonallyopposedleveling
screws.Plunge(rotate)thetelescopesothatthecoincidencevialis
ontopof the telescope, and level the telescopeby eye (Figure2.4).
To assist you, look at the side of the coincidence vial and position
the bubble roughly in the center of its travel.Gently tighten the
Figure2.2
Figure2.3
Preciseleveling