1 - NGA

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andwith allthMS. S-S6Sk@lrnapbM
Perpadwler to the fineofftiifrf.Most camera
~dthiedadgn vmmmtmed ions
trtmetrogon camera because of the
widespread usage of the Metmgon fens in eerfy
tricamwa photography.
trlmotrogon photogmphy—Saa ta n
camera photography.
trlmmlng ●nd mounting dkgram-A
Sketsh Showii how the prints of a tmndxrrlad
mulfple-fens @rotogrs@ should be scwmcfed to
obtain, h effect, a phofogmph ~ b ● *@
kvra. Thehferrnetim k@mlnfkfom of
d-rises derred to the fducial marks on the
photq~, and is the reauR of the calibration
test for he partkuter camera usxi.
Tropk of Cancer—The nmfhem parallel of
dectinslicm, approximsiefy 23”27 from the
ceksliel equfdor, reached by the Sun at ifs
msximum dedinetkn, or the oorrasPondiW
pedal on the Earth.
Tmpk of Caprlcor-l%e southern parallel
af decfhation, approximately 23%?7 fmm the
cekstiil,equstor, reached by the Sun m *S
maximum dadimlien. or the corresoondnfl
psrallel on the Earth. ”
tropical month—The averege period of the
revolutii of the Moon ebout the Earth with
=Yo the V-l equinox, eppmximatety 27
tropkal yser-The inlervel of time between
k auccaaaive pasaugea of the vernal equinox
by the Sun. The tropical year is the year of the
aaeaone, ard the basis of the conventional
sehdar year. Aiao celled mstronomlc yoer;
●qulrmotlel yOaG natural year; solar
y.mr.
tropopeuse-(JCS) The trandtion zone
bafwaen the atrefosphera and the tmp=phere.
The tmpopauae normally ccwre et en aftiiude of
about 25,000 to 45,tW0 feel in polar and
temperate zones, end st 55,000 feet in the
Impiss. See else atmoephem.
tropotrphera-(JCS) The Imver layers of
atmosphere, in wttich the change of
temperature wilh height is relatively farge. It is
the region where clouts form, oonvediin is
acf”we, end mbrhrg is sonfhuous and more or
lees mmplele. See al= etmosphare.
MIL-HDBK-850
268
tmpospherk ecattor--(JCS) The
LvwM@~ ~ radii vmvee @ edf~ ~ ~
redl d uragikt’kii or diiimitiea in the
pI@d propeti= d the ~.
trough compac-See dtilinatolm.
Troughton level-h Engfiah instrument
hevingffte ePbiflevd Permar@b’af@=ffo
thetopof fhstelessc$Mtube
true ●ltitude-1. (.ES) The height of an
airsrdf sa measured from mean sea level. 2.
The actual eftiitde of a selaatii kc+ above the
celasfhf horizon. Mao died observed
●ltitude.
true amplltude-A@dude retetive to true
aasl or weat. See also emplltuda.
trua enomaly—See anomaly, definition 3.
true azimuth-The horizontal dkest”kn of any
line measured cleckwiae fmm true north.
true bfaering-The horizontal angle between
the meridiin tine and a line on the Eerth. The
term true baarlng is used in many cd the aerly
descriptimrs of tand boundaries in the Uniied
Stales. n Lseeeec4ated with true north, referring
to the direction of the ninth psint ee determined
by astrrmomlc observations. ff an estmnomkatty
delemtined bearing ie used, howwer, the term
mstronomlc boarlng is prefemed over true
bearing.
true dspresslon ●ngle-l%a setting of the
obtlque oemama kr the phdographk a’kcraft w“kh
retetion tothetrue herbomff~~ byarey
fmm the exposure station through the prirdpal
point et the abhque phdogmph and a my to the
true horizon.
true dlractlo~rizontal diresttin espraeaad
as angular dist- fmm true north.
true error—See resultant ●rror.
true horizon—(JCS) 1. The baundery of a
horizontal plane pesslng through e point of
vision. 2. In pholograrnmetry, the boundary of a
horizontal plane passing thrwgh the
parap~~a center of e lens system. See also
horizon trace.
true llne-A line of con.stani bearing (rhumb