The text introduces us to the story of photography as a medium for scientific observation through its difficulties and developments during the 19th and 20th century.
Focusing on the study case of the transits of Venus in 1872 and 1874 the author narrates the struggles and challenges of astronomers to produce images and typologies that would be sufficiently objective to serve the purposes of scientific measurement and analysis.
The problems of the medium were diverse and complex, astronomers had to deal with variables such as emulsions, exposure time and standardization that is required to make scientific data comparable. All these variables affected directly the construction of a typology. As stated in the text: With new emulsions came adjustments in the evaluation of observations, and many conflicts about the “success” of a given observation when it was conducted photographically (p.20).
Even scientist following the same method could end with different results. As an example, the text mentions the images of the six plate negatives of the Venus transit (illus.14). These images were taken using the same photographic method but resulted in different colors and densities. Daguerreotype (and its variations of emulsion recipes and plates) became a practical method for astronomic photography. Even so, for some scientist image results could be a success while for others useless and unreliable.
However, this complex issue did not hold back scientists to keep using photography as a tool for observation. The studies of motion, the invention of X-rays and photogrammetry (just to name a few) offered new methods to measure, capture, document, and observe a world that before the invention of photography was not even conceivable.
The idea of absolute objectivity linked to the mechanical nature of the camera is long gone. Photography has become something else. I don’t conceive photography as an objective medium but as a construct. There is no truth embedded in the photographic image or act. In our contemporary world, it is important to understand and acknowledge the myriad of possibilities involved in photography: It is important to look at images carefully, to understand the sources and the context (either social, cultural or in scientific or artistic practices) in which images are produced. This is particularly urgent in our times of mass/social media and technological outbreak.