Photographing and Printing the Cosmos
The telescopic and photographic technology available to astronomers at the time had many limitations in comparison with today's imaging technologies. Because the earth moves, observers had to carefully guide their telescope throughout the night in order to create a "static" image of the object under observation; this was difficult to accomplish, especially given the length of time required to capture the light of these distant bodies, and the resulting images were often blurry. The process of guiding the telescope was especially tricky in the case of comets, the trails of which often appeared "ragged," according to the Lick's first primary photographer, Edward Barnard; for more about Barnard's experiences, see the photo in Case 1 and this article on his experiences with astrophotography at the Lick. In an early reflection on the merits of astrophotography, one page of which is displayed here, Charles Perrine also discusses the difficulty of capturing the light of celestial bodies. For the full article, see our digital exhibit.
Most of the images produced in the early years of the astronomy's activity were made on small glass plates measuring 3.25" by 4.25". As you can see with the plates displayed here, the images were very small--stars often measuring only millimeters in diameter on the plate. In addition to the problem of created by the motion of the earth and the telescope, then, the resolution and "sharpness" of the initial image was low, which made it difficult to enlarge the image, as you can see in the photograph of the spiral nebula. This problem was exacerbated by the technologies used to reproduce the images. Two technologies were available, called half-tone and photogravure, both of which had limitations when it came to producing a "faithful" reproduction of the original glass plate positive or negative. Astronomers, working within certain ideas about what the cosmos looks like and how to best represent it, often had many complaints--the loss of light or detail, the lack of "snappiness" or contrast, the artifact of ragged gradation created by the half-tone process, the "thinness," lack of depth or "darkness" of the sky behind the object pictured. They often required the printers to try again, yet then complained that the prints were too retouched and therefore not objective pieces of data. To see more of the letters exchanged between Lick directors and printing companies, see our digital exhibit.
These images and documents tell us how difficult it was for astronomers to create these early images of the cosmos, speaking to a certain intensity of labor on the part of the individual astronomer and the technicians that would assist him or her in the process; but they also tell us how the aesthetic expectations and concerns of the Lick's astronomers conditioned both the way the images were created and the way they were reproduced as prints. Additionally, they also archive another story about how these aesthetic concerns impacted the labor of the printers in meeting the expectations of the Lick's directors.
