539
a rack and pinion system and checked with a magnify-
ing glass—was Voigtländer’s all-metal camera design
of 1840. Fitted with Petzval’s remarkable f3.7 doublet
lens, and taking circular daguerreotypes of 80mm di-
ameter, this camera was, probably, the fi rst camera to
permit truly precise control over focus. The considerably
reduced depth of focus afforded by the faster lens, of
course, made precise focusing a much greater necessity
than the smaller aperture lenses used on other, larger-
bodied, contemporary cameras.
Voigtländer’s rack and pinion focusing system re-
appeared on the Bourquin daguerreotype camera of
1845—as did Petzval’s doublet portrait lens.
During the 1840s, it became normal for cameras de-
signed for external use to be focused by simply sliding
the box. For studio cameras, with their faster lenses and
larger apertures, where more precise focus was desir-
able, the camera would fi rst be crudely focused using
the sliding box, then fi ne focused using either a rack
and pinion adjustment on the lens barrel, or a simple
helical device.
A radically different approach was that taken by Al-
exander S Wolcott, whose camera design eschewed the
whole idea of a lens in favour of a concave mirror—a
system used in generations of refl ecting telescopes.
The mirror, fi xed inside the camera body, collected the
light rays and focused them on to a small daguerreotype
plate—never bigger than 1/9th plate. To achieve sharp
focus, it was the plate carrier that was adjusted along a
sliding track inside the camera body.
George Knight marketed a variation on the ‘American
Camera’ in the early 1840s, the two sliding boxes be-
ing of suffi cient length, when extended, to enable 1:1
focusing. Knight’s catalogue described the camera as
offering “great variation in the length of focus and may
be used for copying daguerreotypes where the focus is
required to be the same length as the object to be copied
is distant from the object glass.”
With the introduction of bellows in the 1850s, rack
and pinion focusing along baseboard rails eventually
became the norm—with some cameras offering lens
panel focusing and others adjusting the focus by mov-
ing the back panel. By the 1860s, cameras appeared
permitting adjustment on either standard.
The introduction of lens designs offering variable ap-
ertures—designs by Waterhouse, Quinet, Chevalier and
others were introduced in the 1850s and 1860s—gave
photographers hitherto impossible control over the depth
of fi eld, and thus gave them control over the plane of
focus itself. It was 1886, with the introduction of Lan-
caster’s Rectigraph lens of 1886, before a lens with an
iris diaphragm was fi rst widely marketed.
With the introduction of enlargers, and the progres-
sive reduction in negative sizes towards the end of the
19th century, the establishment of precision in focusing
became paramount.
Technical issues of image sharpness occupied a
disproportionately large part of critical reviews of early
photography—where the creation of pinpoint sharpness
in all planes of the image was deemed an essential.
Photographers with their blue sensitive plates initially
struggled with understanding key issues about the differ-
ence between optical and chemical focus, but as the art
matured, and pictorial ideas about soft focus, or selective
focus, rather than sharp focus became talking points, the
challenges which faced photographers expanded.
In this more mature environment, focus became
something the photographer could control, adjust andFOCUSING
Clifford, Charles. Courtyard of
the House Known as Los Infantes.
The Metropolitan Museum of Art,
Gilman Collection, Purchase, Mr.
and Mrs. Hentry R. Kravis Gift, 2005
(2005.100.504.46) Image © The
Metropolitan Museum of Art.