This essay by a historian of science and X-ray crystallographer refutes the claim that Rosalind Franklin failed to see Photograph 51's significance for DNA's helical structure. Rather, Franklin took Photograph 51 precisely because she knew key DNA B form helix parameters could be calculated from it. She had already made those calculations on her earlier Photograph 49 and reused the same DNA sample for Photograph 51 to create a better-centered but otherwise identical diffraction image suitable for publication.
Thus Photograph 51 was not an experiment in need of analysis, but refined documentation for calculations she had already performed. Colleagues and later commentators did not merely overlook Franklin's original reason for creating the strikingly clear image; they rhetorically erased her skill and judgment by describing it as though nature spoke for itself through the image—and to Watson, but not to Franklin. While Watson's memoir made Photograph 51 famous, his story gave the impression that Franklin had not recognized its significance.
By consensus, Franklin put Photograph 51 aside and did nothing with it, instead devoting months to studying DNA's A form. However, Franklin had already captured a B form pattern in Photograph 51 by accident and considered it a distraction. For Horace Judson, this added up to willful deafness on Franklin's part, lamenting that the pattern shouted helix but she 'turned her back on her own discovery' for nearly ten months.
We contend that Photograph 51 shouted 'helix' so clearly because Franklin intended it to do so.
Source: Hacker News · Summarized by HeadlinesBriefing