Depth of Field

… Old-fashioned, direct observation could see deeper into the sample; it allowed movement of the sample from side to side; it could integrate the basic facts and details; and it could make quick comparisons by moving back and forth between neighboring sites.

… The photomicrographer can coax details into the picture, heighten them — or let them escape. “We can assert that a photograph can only lay claim to objectivity if it is produced by an honest, gifted micro-photographer, working according to all the rules of the art, and richly endowed with patience and skill.”

This is from Objectivity by Lorraine Daston and Peter Galison (2007):

… Was mechanical objectivity ever completely realized? Of course not, and its advocates knew they faced a regulative ideal. That is, they saw objective depiction in their sciences as a guide point. If they could replace speculation with close observation of an individual, that was good. If they could find a procedure that would hem in freehand drawing, even better. And if they found a way to minimize interpretation in the process of image reproduction — better still. It is easy to assume that objective depiction was either an ideal or consequential — but it was, in fact, both. Analogously, fairness in the organization of a game may never be complete, but it can nonetheless shape the procedures that its participants adopt.

… In ordinary observation (said Fraenkel and Pfeiffer), all too often the observer simply gets a general impression of the forms of bacterial colonies growing on the gelatin plate — and then, on the basis if this cursory look, declares that he is done with his investigation. In a photograph, this frequently unjustified winnowing of the “important” from the “unimportant” will not stand. Reexamining the photograph can lead the scientist to reevaluate what is actually in the image. The photomicrograph acts pedagogically by extending — in fact revising — the process of observation. In short, the photomicrographic trace becomes an archive as a drawing could not; the photograph is a resource for further inquiry.

The Hygienics Institute micrographers readily conceded, however, some serious disadvantages. First, the photographic plate could capture only a narrowly bounded fraction of the preparation. Worse, because of its limited depth of field, the photograph could show essentially a single focal plane — and at the edges of the sample, the image blurs. Old-fashioned, direct observation could see deeper into the sample; it allowed movement of the sample from side to side; it could integrate the basic facts and details; and it could make quick comparisons by moving back and forth between neighboring sites. By looking long, hard, and intelligently, the observer can sort out the structural relations and the mechanical construction of the object. The detailed accumulation of bacteria in a large-scale colony is beyond — at least beyond any easy — representation with photomicrography. To look at a failed plate with its blurring, its indistinct contours, its interference fringes is to see just how mangled and unrecognizable an image can become.

… Although mechanical objectivity was in the service of gaining right depiction of nature, its primarily allegiance was to a morality of self-restraint. When forced to choose between accuracy and moral probity, the atlas makers often chose the latter, as we have seen: better to have bad color, ragged tissue edges, limited focal planes, and blurred boundaries than even a suspicion of subjectivity. The discipline earlier atlas makers had imposed on their artists had been in the interests of truth, which could only be discovered by sagacious selection of the typical or characteristic. Truth did not lie on the visible surface of the world. Later atlas makers, as fearful of themselves as of their artists, forfeited the typical and postponed an immediate grasp of truth because intervention was needed to produce it and because alteration of the image led all too easily to the dreaded subjectivity of interpretation.

… Richard Neuhauss, one of the great nineteenth-century experts on photomicrography, titled a key section of his treatise on photomicrography “Retouching the Negative.” … According to Neuhauss, it is not the photographer’s image but nature’s that is wanted. This was easy to say but hard to realize: sensu stricto, every alteration of the natural ought to be forbidden. but Neuhauss knew far too much to pretend to this ideal. Anyone could see that two identical photographic plates, exposed in identical light conditions, could be developed to produce radically different images; one plate could show, for example, subtle, fine structures that the other obscured.

…” … the light sensitive plate copies everything that does not belong to the object with frightening objectivity — such as the impurities of the preparation and the diffraction edges.” (Not to mention dust particles, plate defects, Newton’s rings, and a host of other artifacts.) Too much light or too little light made details vanish. Developing the film introduced still more difficulties:membranes appeared more than once in one image and disappeared in another. “This is the objectivity of the microphotogram!” Neuhauss ruefully concluded. The photomicrographer can coax details into the picture, heighten them — or let them escape. “We can assert that a photograph can only lay claim to objectivity if it is produced by an honest, gifted micro-photographer, working according to all the rules of the art, and richly endowed with patience and skill.” After forty years of scientific photography in the service of mechanical objectivity, Neuhauss knew that the photographer’s art must aid science; skill wa needed where automatism came up short.

I first posted this without comment, but I find that I want to point out, in case you missed it, what is implied in this bit from the first paragraph, “fairness in the organization of a game may never be complete, but it can nonetheless shape the procedures that its participants adopt.” The rules of games are arbitrary and made-up; they’re whatever you want them to be when you invent the game.

-Julie

http://www.unrealnature.com/