HF The History of Photography 600pág

420 The gelatine period
Enough has been said to show that the industry enjoyed the greatest boom it ever
had. New apparatus appeared on the ni.arket almost every week, for the ranks of
photographers also swelled from week to week. And the end was still unforeseeable.
SHUTTERS
Whereas before l 880 it had generally sufficed to use a lens cap, a metal flap fixed to
the lens, or a similar contrivance, quick-acting shutters of variable speeds had to be
employed in conjunction with the new fast negative material and small camera sizes.
Only in conjunction with these small cameras, and especially binocular cameras,
had shutters been necessary during the collodion period. A mechanical shutter consisting
of a revolving metal disk with an opening in it, and set by a spiral spring, was
introduced by ADOLPHE BERTSCH of Paris in 1852. J. B. DANCER patented an improved
version in l 8 56 with three apertures of different sizes acting as stops. In the
188os and 189os ingenious shutters were constructed in the form of metal segments
or revolving disks set by springs and released by a pneumatic bulb, pneumatic
guillotine shutters, and roller-blind shutters. They were all fixed in front of the lens,
and gave variable speeds from l to 1
6 0 second according to the degree of pneumatic
pressure or spring tension. In hand cameras, the unwieldy drop and flap shutters were
soon superseded by diaphragm or sector shutters incorporated in the lens-usually
between the lens combinations. The Compur shutter devised by the Munich firm
Friedrich Deckel in 1912 was a development of the same firm's earlier Compound
shutter (1902). It is today universally fitted to good-quality hand cameras permitting
exposures of down to 5
6 0 second.
The focal-plane shutter, which is incorporated in all modern high-speed cameras,
is a behind-the-lens shutter. The origin of this shutter is often erroneously attributed
to the German photographer Ottomar Anschutz, because he included it in his camera
patent of 1888, and C. P. Goerz subsequently fitted the popular Goerz/Anschiitz press
camera (see chapter 36) with such a shutter. But the focal-plane shutter with variable
slit goes back to 1861 and is the invention ofWlLLIAM ENGLAND. England used it for
his instantaneous street views with tannin dry plates, and he described its mechanism
to the Photographic Society of London in April 1862.10 Seventeen years later B. J.
Edwards reintroduced the focal-plane shutter as the most suitable for fast gelatine
plates, demonstrating it before the South London Photographic Society in November
1879.11
EXPOSURE METERS
In the collodion period exposures were still measured in minutes ; they could be
judged by experience inasmuch as each photographer employed, and indeed made,
his own sensitive coating year in year out. The fact that in the gelatine period exposures
had fallen to fractions of a second would probably not in itself have caused
any problems, since the vast majority of amateur cameras were fitted with very
simple shutters with three or four speeds, which were set according to the weather,
time of day, and type of subject-very much as they are today. No, the difficulty that
worried the serious photographer was the impossibility of knowing the speed of the
negative because there existed no standardization amongst manufacturers. Plates and
films were not marked with speed numbers, and great variations existed between
different makes, and even between production batches of the same manufacturer.
DR FERDINAND HURTER, a Swiss chemist working in England from l 867 on, and
his colleague VERO CHARLES DRIFFlELD were also amateur photographers, and tried
to solve the problem of speed rating. Having first devised an actinograph-a kmd ot