[400] American, unidentified. "Portrait of a Lady." (1 film).

Film and glass plate negatives make up this series, and with the corresponding index cards, offer the most complete record of Rosen's photographic studies and restoration work. Rosen apparently numbered the negatives in the order in which he photographed the paintings, making his studies of Daumier his first project. With a number assigned to each painting, the various photographic techniques used on each work of art were coded as alphabetical extensions to each number. Every negative is marked with its numerical/alphabetical code, and the complete description of codes and photographic techniques is recorded on the corresponding index card.

In making infrared studies, Rosen originally used glass plate negatives, in 5x7 and 8x10 formats. He later switched to film negatives. For all other photography, including raking (cross) light and X-ray, Rosen primarily used film negatives, most of which are 5x7. A few of the 8x10 glass plate negatives are identified as "process X-rays," as opposed to the film versions he identified as "ortho X-rays." The third set of negatives are larger X-rays, measuring 13"x16" approximately, and all images are of objects held at this museum. Rosen apparently took these X-rays at his laboratory at the Walters Art Gallery, which forwarded the negatives to the museum after Rosen's death. Most of these negatives therefore have two numerical codes. The original Walters numbering is the four-digit one. The museum's number carries an "XR" prefix. Some of the X-rays are identified by the Walters number only. All film negatives are diacetate, and currently approximately half are in a state of deterioration that prohibits access and any print development.

While most of the photographic subjects are individual works of art, a few negatives depict certain galleries housing the Johnson Collection as well as the wax tank in the Johnson conservation shop and other laboratory set-ups identified as "Shop" photographs. There are also several sets of X-rays of mummies. There appear to be corresponding prints in the first subseries to approximately half of all negatives. In addition to the negatives specifically made in slide format, many other film negatives also appear to have corresponding lantern slides, which comprise another subseries. Folder titles for those prints and slides include Rosen's numerical coding.

In addition to Rosen's original negatives, there are same-size and reduced duplicates for approximately 200 images. These were made in 2004 for conservation purposes.