It’s a great loss that the enthusiastic often give up for want of ready acumen, when enthusiasm is quite what keeps one going. -K
It’s quite going to put some people out to know there is no getting around having some talent when it comes to producing a micrograph. At its worst its no different than drawing from life, though at the best it may be compared unfavorably to tracing. The are as many tools for assistance as one could want, yet no substitute for that ability that only comes of practice. Very briefly the most common apparatus will be touched upon in this series with special focus on the principles, as they apply regardless of the tools.
The difficulty of drawing is as much a matter of recognizing position and the relationship between objects as it of gaining the mechanical skill that comes of practice. while skill counts, that comes with time; placing things accurately is something one can begin from the very start. This bears mention because many people will come to micrography with the impression that the tools provided for it will permit ready ability in producing a fine illustration. For the most part, all the tools involved provide only the outlines, dimensions, and relative positions of specimens, the detail being filled in by ones eye alone. This may appear a great imposition to some but it is worth remembering that there is a world of difference between the requirements of a micrograph and a photomicrogrpa; subsequently, one should consider ones intent and goal.
While at times a full and detailed sketch is required, more often than not one may wish only to capture a particular area or structure in any detail. Still other times one may need only to make a measurement, which is very quick to do provided preliminary gymnastics are performed ahead of time. Some apparatus requires considerable preparation, more than photomicrography even, so ones intent should align with ones purposes at the outset. While digital photomicrographic apparatus has lately turned imaging into a spur of the moment thing, the old methods simply do not allow it.
Since ones needs may vary it is not unlikely that ones tools should vary as well. Some of the tools will surely prove challenging, and the various sorts of camera lucida though all operating on the same principal, have their own vagaries inherent to their construction. It is important however, to learn well the tools one possesses, there being enough expense and difficulty in the acquiring. The tools may be thrown into a few broad categories:
- Those which facilitate free hand drawing.
- Those which project an image from the microscope onto a drawing surface.
- Those which project an image of the drawing surface onto the plane of the image formed by the microscope.
In the first group one will find any of various graticule’s which divide the field of view so that it may be reproduced on a similarly divided drawing surface. It is not unlike the methods a draftsman would use to produce and enlargement or reduction, or a painter would use in copying a landscape from a photograph with a ruled transparency and canvas. The one pictured below dates to the early 1900’s and has only the very center portioned ruled. Modern equivalents may be had in numerous forms from all major makers. A graticule of this sort is placed onto the diaphragm of an eyepiece (generally Huygenian) and focused by minor movement of the eye lens.
The second group includes any of the various methods of producing a microprojection. Mirrors, prisms, and projection eyepieces may all be placed in this category together with the specialized projection microscopes and old form plate photomicrographic apparatus (used as a camera obscura), the photographic plate being replaced by a glass and bit of paper. This first photo depicts two forms of projection head by Bausch & Lomb here seen with the microscope horizontal the size of the projection moderated by the distance of the microscope from drawing surface. That on the left consists of a mirrored right angle prism with a few degrees of movement either direction of forty-five. That on the right is a collard mirror which can accommodate any angle and therefore wider angle of drawing surfaces. The second photo shows a Bausch & Lomb model N photomicrographic head with medium format attachment, being just the size for drawing on a 3×5 index card.
The third group would consist primarily of the various forms of camera lucidas proper, as well as the items operating on the same principle. These are by far the most well known of all the drawing tools and the forms which they take vary wildly. From the Gunrow, and Wollaston’s, to the myriad forms of simple reflector and Abbe camera ludica, the diversity of forms is simply incredible. Abbe’s camera lucida is the most common and frequently available. Shown below are two forms on the Abbe Camera lucida. In the version on the left one is only permitted to incline the drawing surface on a single axis and is limited in its position from the microscope as the reflector is rigidly fixed. The older form on the right permits the mirror to be placed at any angle as well as any distance so that the position of the drawing surface may be made convenient.