Amateur Photographer - UK (2019-07-26)

subscribe 0330 333 1113I http://www.amateurphotographer.co.ukI 20 July 2019 53

Tech Talk

ofessorNewmanon...

BobNewmanis currentlyProfessorof ComputerScienceat theUniversityof Wolverhampton.Hehasbeenworkingwiththedesignanddevelopmentof
high-technology equipment for 35 years and two of his products have won innovation awards. Bob is also a camera nut and a keen amateur photographer.

Space and the

digital camera

T

heApollo 11 landing
wouldnothavebeen
possiblewithouta
completedanddetailed
surveyof thesurfaceof themoon.
Thiswasachievedusingseriesof
surveyingsatelliteswitha camera
systemthathadtwolenses
arrangedin co-axialsystemsothat
bothwereaimedat thesamepoint.
Thelensesprojectedimagesontoa
70mmmonochromefilm.Onelens
wasa Schneider80mmf/2.8,and
thusprovideda ‘normal’image.
Theotherwasa 610mmf/5.6lens,
andwasthusa telephoto.When
exposedthefilmwasadvanced
andtheusedframesautomatically
developedusinga singlebath
process.Toreturntheimage,it was
mechanicallyscannedat what,at
thetime,wasanextremelyhigh
resolutionandtransmittedbackto
Earth.Thefilmthusservedboth
asa meansof imagecaptureand
storage.Thesatellitesreturned
2,180high-resolution(telephoto)
and 882 medium-resolution
(normal)images.
Theresultwasa sufficiently
detailedlunarmapto allow
theApollomissionsto proceed.
However,asa strictlyanalogue
imagingdevice,thesatellitesdid
notthemselvescontributeto the
development of digital photography.

However,thespaceprograms

wereoneof themajordriversof

digitaldevelopment,alongwith

militaryespionage.Thiscanbe

tracedbackto1960,whenthe

firstweathersatellite,TIROS-1

(TelevisonInfraredObservation

Satellite)waslaunched.This

wasananalogsystem,butwas

completelyelectronicand

separateddatacaptureand

storage.It wasbasedon‘slow-

scan’television,a systemthat

wasat thetimepopularwithradio

hams.Theproblemwashowto

transmittelevisionimagesoverthe

limitedamateurbandsavailable.

Recordedimages

Theanswerwastoreducethe

scan-rateof thetelevisionbya

factorof 500orso,allowing

thesignaltousestandardaudio

bands,andasa happysideeffect,

berecordedonordinarytape

recorders.Thiswasexactlywhat

TIROSdid.It hadtwo^1 ∕ 2 inVidicon

cameras(aboutthesameframe

sizeasa moderncompactcamera

orhigh-endphone):onewith

a ‘normal’lensandonewitha

telephotolens.Thecaptured

imageswererecordedontoan

internaltapeloop,andtransmitted

whenthesatellitewasin touch

with a ground station.

TheTIROSsatelliteswerevery

successful,andTIROS-1is still

in orbitnearly 60 yearslater,

thoughnolongerfunctional.

However,thevacuumtube

imagerandtapeloopwere

hardlysatisfactorysolutionsto

theproblemof satelliteimaging.

Thesolutionwasfoundin the

Charge-CoupledDevice,a means

of scanningthousandsormillions

of photocellsintegratedontoa

singlewaferof silicon,developed

in 1969byWillardBoyleand

GeorgeSmithof BellLaboratories.

By 1976 thetechnologyhad

advancedtoallowa 700pixel

square(0.5megapixel)imagerto

beincorporatedintotheKH-11

Kennenreconnaissancesatellite.

Thedetailsarestillclassified,but

it seemsthatit wastheprototype

fortheHubblespacetelescope,

equippedwitha similar2.34m

mirrorasitsprimaryobjective.This

offersa verynarrowfieldof view,

andthereis nodirectequivalentto

thewidefieldcamerasontheLunar

OrbiterandTIROSsatellites.Buta

similareffectcanbesynthesisedby

usinga mosaicof thenarrowview

images,bythisstagesemiconductor

technologyhavingadvanced

sufficientlytoallowsufficient

computationpowerbothtostore

and process these images.

Thespaceprogramsofthe1960sand1970splayed

an essential role in the evolution of digital imaging

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Passionateaboutphotographysince 188

Saturday 6 January 2018

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PORTRAIT SPECIAL rse
ThefirstviewofEarthfromthemoon,takenbyLunar
Orbiter1 in 1966.Thesedaysthescanningartefacts
would be removed with a little image processing
© NASA