Amateur Photographer – 20 July 2019

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

Tech Talk

Professor Newman on...

Bob Newman is currently Professor of Computer Science at the University of Wolverhampton. He has been working with the design and development of
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

ProfessorNewmanon...

Space and the

digital camera

T

he Apollo 11 landing
would not have been
possible without a
completed and detailed
survey of the surface of the moon.
This was achieved using series of
surveying satellites with a camera
system that had two lenses
arranged in co-axial system so that
both were aimed at the same point.
The lenses projected images onto a
70mm monochrome fi lm. One lens
was a Schneider 80mm f/2.8, and
thus provided a ‘normal’ image.
The other was a 610mm f/5.6 lens,
and was thus a telephoto. When
exposed the fi lm was advanced
and the used frames automatically
developed using a single bath
process. To return the image, it was
mechanically scanned at what, at
the time, was an extremely high
resolution and transmitted back to
Earth. The fi lm thus served both
as a means of image capture and
storage. The satellites returned
2,180 high-resolution (telephoto)
and 882 medium-resolution
(normal) images.
The result was a suffi ciently
detailed lunar map to allow
the Apollo missions to proceed.
However, as a strictly analogue
imaging device, the satellites did
not themselves contribute to the
development of digital photography.

However, the space programs

were one of the major drivers of

digital development, along with

military espionage. This can be

traced back to 1960, when the

fi rst weather satellite, TIROS-1

(Televison Infrared Observation

Satellite) was launched. This

was an analog system, but was

completely electronic and

separated data capture and

storage. It was based on ‘slow-

scan’ television, a system that

was at the time popular with radio

hams. The problem was how to

transmit television images over the

limited amateur bands available.

Recorded images

The answer was to reduce the

scan-rate of the television by a

factor of 500 or so, allowing

the signal to use standard audio

bands, and as a happy side effect,

be recorded on ordinary tape

recorders. This was exactly what

TIROS did. It had two^1 ∕ 2 in Vidicon

cameras (about the same frame

size as a modern compact camera

or high-end phone): one with

a ‘normal’ lens and one with a

telephoto lens. The captured

images were recorded onto an

internal tape loop, and transmitted

when the satellite was in touch

with a ground station.

The TIROS satellites were very

successful, and TIROS-1 is still

in orbit nearly 60 years later,

though no longer functional.

However, the vacuum tube

imager and tape loop were

hardly satisfactory solutions to

the problem of satellite imaging.

The solution was found in the

Charge-Coupled Device, a means

of scanning thousands or millions

of photocells integrated onto a

single wafer of silicon, developed

in 1969 by Willard Boyle and

George Smith of Bell Laboratories.

By 1976 the technology had

advanced to allow a 700 pixel

square (0.5 megapixel) imager to

be incorporated into the KH-11

Kennen reconnaissance satellite.

The details are still classifi ed, but

it seems that it was the prototype

for the Hubble space telescope,

equipped with a similar 2.34m

mirror as its primary objective. This

offers a very narrow fi eld of view,

and there is no direct equivalent to

the wide fi eld cameras on the Lunar

Orbiter and TIROS satellites. But a

similar effect can be synthesised by

using a mosaic of the narrow view

images, by this stage semiconductor

technology having advanced

suffi ciently to allow suffi cient

computation power both to store

and process these images.

The space programs of the 1960s and 1970s played

an essential role in the evolution of digital imaging

Subscribe online at

magazinesdirect.com/18AG

0330 333 1113

Quote code: 18AG

Lines open Monday – Saturday, 8am-6pm (UK time)

*Pay just £24.99 by Direct Debit every 3 months,

with the price guaranteed for the first 12 months

and we will notify you in advance of any price

changes. Offer closes 30th September 2019.

Terms and conditions apply. For full details please

visit http://www.magazinesdirect.com/terms

• Never miss an issue
  with delivery
  direct to your door


• Peace of mind with
  our money back
  guarantee if you
  change your mind


• Access to exclusive
  offers, giveaways
  and prizes with
  subscriber Rewards

Subscribe to

Amateur

Photographer

for just

£24.99

• 
  

saving 35%

Passionate about photography since 1884

Saturday 6 January 2018

The perfect small camera bag Lovely new Billingham ticks the boxes

Leica CLWhy this gorgeous rangefi nder-style

camera is Leica’s best mirrorless yet

One face

50 ways

TESTED

Fresh approaches for creative portraits

APOY ’s topportraits

Which did well, and why?people shots

Top-notch Tokina

Superb fast 20mm prime tested

Collodioncreativity

A modern twist on a classic technique

Passionateabout photographysince 1884

BUYI NG 12-page

vsulixcEGUIDE& lensescameras 597

e^ money-saving off

PORTRAIT SPECIAL rse

The first view of Earth from the moon, taken by Lunar

Orbiter 1 in 1966. These days the scanning artefacts

would be removed with a little image processing

© NASA