DK Eyewitness Books Invention by Unknown

Author:Unknown
Language: eng
Format: epub, pdf

The wet plate

Chemicals for

From 1839 on, the pioneers of photography

wet-plate process

concentrated on the use of salts of silver as

the light-sensitive material. In

1851, Frederick Scott Archer

created a glass photographic

plate more light-sensitive than

its predecessors. It recorded

negative images of fine detail

with exposures of less than

30 seconds. The plate was coated

with a chemical mix, put in the

Wet-plate negative

camera, and exposed while still

wet. It was a messy process, but

gave excellent results.

Plate holder

CHEMICALS above right

A wet plate consisted of a glass

sheet coated with silver salts

and a sticky material called

collodion. It was usually

developed with pyrogallic acid

and fixed with sodium

thiosulphate (“hypo”).

Chemicals were dispensed

from small bottles.

IN AND OUT OF VIEW

This wet-plate camera was

mounted on a tripod. The

rear section into which the

photographic plate was

inserted could slide toward

or away from the front lens

section to increase or

decrease the image size and

produce a clear picture. Fine

focusing was by means of a

knob on the lens tube.

Modern photography

PHOTOGRAPHY FOR ALL

In the early 1900s

In the 1870s dry gelatine-coated

Eastman developed

inexpensive Brownie box

plates covered with extremely

cameras such as this, and

light-sensitive silver bromide

amateur photography

were developed. Soon more

was born. Each time a

sensitive paper allowed many

photo was taken, you

would wind the film

prints to be made from a

to be ready for the

negative quickly and easily in a

next shot.

darkroom. In 1888 George

Eastman introduced a small,

Film winder

ROLL FILM

lightweight camera. It used film

Eastman’s early roll film

which came on a roll.

Viewfinder

consisted of a long thin

strip of paper from which

the negative coating was

CANDID CAMERA right

Film

stripped and put down on

By the 1920s German optical

winder

glass plates before

instrument manufacturers such as Carl

printing. In 1889 celluloid

Zeiss were developing small precision

roll film came on the

cameras. This 1937 single-lens reflex

market. The light-sensitive

Lens

(SLR) Exakta model is in many ways the

emulsion was coated onto

forerunner of a whole generation of

a see-through base so

modern cameras.

that the stripping process

SLR camera

was eliminated.

41

(c) 2011 Dorling Kindersley. All Rights Reserved.

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