9. Photography
9.1. Introductory Remarks
The electron microscope is fundamentally a camera, and the electron
micrograph is its product. To achieve the latter we have the basic problems of any photography. Thus, this is one of the several skills in which
an electron microscopist must acquire proficiency.
The first commercial microscopes in widespread use were, of course,
the post-war RCA EMU-2 instruments. These were built to accommodate
2 X 10 in. plates which have proved to be a fortunate choice. This curiously sized plate was and is manufactured with a variety of fine grained
emulsions, for it is of standard dimensions for much spectrographic work.
The Eastman Kodak Co. "lantern slide" emulsion was recommended
from the outset and hardly has been improved upon since.
The microscopist need not anticipate difficulty with commercially
available photographic materials. His difficulties will lie in other directions. Most particularly he will find that focusing is a very serious problem, and also he will have to learn how to judge the image on the
fluorescent
screen so that he selects sections of suitable thickness and,
in other ways, adequate for the task at hand.
It is obvious that only a small fraction of what the observer sees on
the fluorescent screen of the microscope can be recorded on photographic
film. Indeed, the time it takes to focus and otherwise adjust the microscope for picture taking, and to replace exposed plates, is a major production bottleneck. Inevitably, then, every electron micrograph of a tissue
section represents a highly selected field. So much judgment is involved
in the selection that it ordinarily cannot be delegated to technical help.
The bacteriologist or virologist who has thousands of units all essentially
alike might be able to do this. But the histologist who deals with ever
changing patterns usually must expect to spend many hours looking at
the fluorescent screen of the microscope, and to take dozens of micrographs before he can feel confident that he has understanding and adequate records of any particular specimen. This makes any comparative
study very slow; for days and even weeks may be devoted to a single
sample. It is apt to be difficult to make the uninitiated appreciate this.
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9.1. Introductory Remarks
The electron microscope is fundamentally a camera, and the electron
micrograph is its product. To achieve the latter we have the basic problems of any photography. Thus, this is one of the several skills in which
an electron microscopist must acquire proficiency.
The first commercial microscopes in widespread use were, of course,
the post-war RCA EMU-2 instruments. These were built to accommodate
2 X 10 in. plates which have proved to be a fortunate choice. This curiously sized plate was and is manufactured with a variety of fine grained
emulsions, for it is of standard dimensions for much spectrographic work.
The Eastman Kodak Co. "lantern slide" emulsion was recommended
from the outset and hardly has been improved upon since.
The microscopist need not anticipate difficulty with commercially
available photographic materials. His difficulties will lie in other directions. Most particularly he will find that focusing is a very serious problem, and also he will have to learn how to judge the image on the
fluorescent
screen so that he selects sections of suitable thickness and,
in other ways, adequate for the task at hand.
It is obvious that only a small fraction of what the observer sees on
the fluorescent screen of the microscope can be recorded on photographic
film. Indeed, the time it takes to focus and otherwise adjust the microscope for picture taking, and to replace exposed plates, is a major production bottleneck. Inevitably, then, every electron micrograph of a tissue
section represents a highly selected field. So much judgment is involved
in the selection that it ordinarily cannot be delegated to technical help.
The bacteriologist or virologist who has thousands of units all essentially
alike might be able to do this. But the histologist who deals with ever
changing patterns usually must expect to spend many hours looking at
the fluorescent screen of the microscope, and to take dozens of micrographs before he can feel confident that he has understanding and adequate records of any particular specimen. This makes any comparative
study very slow; for days and even weeks may be devoted to a single
sample. It is apt to be difficult to make the uninitiated appreciate this.
299