John Thomson's Primary Camera: The Wet Collodion Process

John Thomson, the Scottish photographer who documented street life in London and Asia during the 1870s and 1880s, did not use a single camera model the way modern photographers do. Instead, he worked with large-format cameras that used wet collodion glass plates—a photographic process that required him to coat, expose, and develop each plate on the spot or within hours. This was not a portable snapshot camera; it was a studio-quality system adapted for outdoor work.

The wet collodion process meant Thomson carried glass plates, chemical baths, a darkroom tent, and heavy wooden camera bodies. His street photography was not candid in the modern sense. Subjects had to hold still for several seconds while the shutter was open, and Thomson often worked with an assistant to manage the chemistry and equipment. The camera itself was typically an 8x10-inch or 10x12-inch format—large enough to capture fine detail but demanding in weight and setup time.

Thomson's choice of this technology was not unusual for his era. Wet collodion was the standard for serious documentary photography in the 1870s. What made Thomson distinctive was his willingness to haul this cumbersome system into crowded streets, narrow alleys, and working-class neighborhoods rather than confining it to a studio.

Key Takeaways

  • Thomson used large-format wet collodion cameras, typically 8x10 or 10x12 inches, which required glass plates and chemical processing on location.
  • Wet collodion was the standard photographic process of the 1870s and 1880s, not a choice unique to Thomson, but his process to street photography was pioneering.
  • His camera system was heavy and required an assistant to manage chemicals, darkroom tents, and plates—street photography then was a multi-person operation.
  • The slow exposure time meant subjects had to remain still, so Thomson's street scenes were semi-posed rather than truly candid by modern standards.

How Wet Collodion Cameras Worked in the Field

A wet collodion camera required Thomson to prepare a glass plate by coating it with a light-sensitive chemical emulsion just before use. He would load the plate into the camera, make his exposure (typically 3 to 10 seconds depending on light), and then develop it when ready in a portable darkroom tent or a nearby building. This meant he could not straightforward walk around with loaded plates; each photograph was a deliberate, time-consuming process.

The camera body itself was usually made of wood with a brass lens and a straightforward shutter mechanism. Thomson likely used lenses in the 8-inch to 12-inch focal length range, which on an 8x10 format would give him a moderate wide angle suitable for street scenes. The wooden body was not weatherproof, so rain or extreme humidity posed real problems. The glass plates were fragile and heavy—a day's work might involve carrying 12 to 20 plates, each one a potential loss if dropped.

This setup explains why Thomson's street photographs, while groundbreaking in subject matter, look formally composed compared to street photography from the 1920s onward. By the time handheld cameras with fast film became available, photographers could capture genuine spontaneity. Thomson had to work within the constraints of his technology, which meant asking people to pause, positioning himself carefully, and waiting for the right light.

Thomson's Work in London and China

Thomson's most famous street photography comes from two periods: his work in London's poor neighborhoods in the 1870s, published as Street Life in London, and his earlier travels in China, Siam, and Cambodia in the 1860s. In both places, he used the same wet collodion system, though the logistics were far more difficult in Asia, where he had to transport chemicals, glass plates, and equipment across difficult terrain and manage them in tropical heat and humidity.

In London, Thomson photographed street vendors, laborers, children, and the urban poor. His camera allowed him to record fine detail—the texture of clothing, the expressions on faces, the arrangement of goods in a street stall. The large negative size meant he could enlarge prints to substantial dimensions without losing sharpness, which made his work powerful for publication and exhibition.

Thomson's approach to street photography was documentary rather than artistic in the pictorialist sense. He was interested in recording how people actually lived and worked, not in creating romantic or sentimental images. His camera was a tool for social observation, and the technical limitations of wet collodion did not prevent him from achieving that goal—they straightforward shaped how he had to work.

Why Large Format Was Necessary for Thomson's Goals

Thomson chose large-format cameras because he needed the image quality and detail they provided. Street photography in the 1870s was not about capturing a fleeting moment; it was about documenting a scene thoroughly enough that viewers could understand the conditions and circumstances of the people in it. A small negative would not have given him the clarity he needed.

The large glass plate also meant he could make contact prints—prints made by placing the negative directly against printing paper—without enlargement. This preserved maximum detail and tonal range. For a photographer working on a documentary project intended for publication, this was essential. Enlargement technology existed but was less reliable and could introduce grain or loss of detail.

The weight and bulk of the system also served a practical purpose: it signaled seriousness. Thomson was not a casual tourist with a snapshot camera. He was a professional photographer with expensive equipment, which gave him credibility when approaching subjects and negotiating access to private spaces or sensitive locations.

The Transition Away from Wet Collodion

By the 1890s, dry gelatin plates and then roll film began to replace wet collodion. These new technologies were faster, more portable, and did not require when ready processing. Thomson's career spanned the transition, though his most celebrated street work was completed before these innovations became widespread. Younger photographers who came after him had access to cameras that were lighter, faster, and more flexible—advantages that would reshape street photography entirely.

The shift from wet collodion to dry plates and film is one reason Thomson's street photographs look different from those made even 20 years later. It is not that Thomson was less skilled or less observant; it is that his technology imposed different constraints. Understanding what camera he used means understanding that his photographs are documents of both his subjects and the possibilities and limitations of 1870s photographic technology.

Frequently Asked Questions

Did John Thomson use the same camera for his work in China and London?

Yes, Thomson used wet collodion large-format cameras for both his Asian travels in the 1860s and his London street photography in the 1870s. The technology was the same, though the practical challenges of transporting and maintaining equipment in tropical climates were much greater in Asia.

Could Thomson's camera capture candid moments the way modern street photographers do?

No. The slow exposure time (several seconds) and the need to prepare each plate meant subjects had to remain still. Thomson's street scenes are semi-posed—people knew they were being photographed and held their position. True candid street photography became possible only after faster film and handheld cameras were developed.

Why did Thomson not use smaller, more portable cameras?

Smaller cameras of that era produced lower-quality negatives. Thomson needed the detail and tonal range that large-format plates provided, especially for documentary work intended for publication. The size was a trade-off he accepted in exchange for image quality.

What happened to Thomson's original glass plate negatives?

Many of Thomson's original wet collodion plates survive in archives, including the Wellcome Library in London. These glass negatives are fragile but have proven more durable than many other photographic materials from the same period, which is one reason Thomson's work remains accessible today.