AN AMATEUR'S APPROACH TO PHOTOMICROGRAPHY MICHAEL
THOMSON
Definition PIIOTOMICROGRAPHY
is photography of an object as enlarged under
the microscope. Introduction This is not intended to be an authoritative article, but an account of the results of experimentation by an amateur in this fascinating field. It is surprisingly easy to obtain an adequate photomicrograph even with simple apparatus. Apparatus A rather old monocular microscope was used at first, but this was later replaced by a more modern binocular model. A 100W. household bulb provided the source of illumination the light being reflected from the plane mirror through a substage condenser. The camera was a 35mm. iris shutter model with speeds varying from 1 /300 to 1 second. Setting up the apparatus Some method had to be found by which the camera could be firmly suspended over the eye-piece of the microscope and yet be easily and quickly swung aside when not in use. Since the subject matter was mainly living organisms, manipulation of the camera over a monocular eye-piece had to be slick in order to catch the organisms, which were rarely obliging ! The advantages of a binocular eye-piece were therefore apparent, as the camera could be arranged over one eye-piece while the operator used the other. The camera was attached, by a boss, to the pole of an upturned retort stand, the base of which was securely clamped between two spars of wood {diagram). This clamp could be relaxed by a butterfly nut to allow the whole camera assembly to be slid side-ways out of the way. The whole assembly was then secured to the walls by chocks. By this simple apparatus it was possible to move the camera in any plane rcquired quickly and smoothly.
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lli preparing to take pictures the microscope was placed so as to bc in a comfortable position for the O p e r a t o r , then the camera was aligned so that it was almost in contact with the eye-piece lens. This allowed the maximum amount of light to get into the camera from the microscope and virtually none from outside. In this respect, while the camera was being used, only the microscope lamp was turned on, and this was shielded to prevent light getting to the film, other than through the microscope.
354 Transactions of the Suffolk Naturalists',
Vol. 12, Part 5
Film and exposure t i m e s A film with a fine grain was found to be the best as it gave good definition to even the smallest objects and enabled the 35mm. negative to be enlarged without the grain showing in the prints. F.P.3. film was found to be perfectly satisfactory. Kodachrome colour film produced amazingly good colour reproduction but with the faster shutter speeds the whole picture took on an orange tint. However the introduction of a blue filter in the microscope condenser improved this defect. No direct method of determining exposure times was found to be practicable, so a series of pictures of the same object was taken with different expoeures, varying the magnifying power of the microscope. From the negatives or slides obtained it was decided which was the best exposure for any combination of eye-piece and lens. For black and white film (F.P.3) with a X 10 objective lens and a X7.5 eye-piece, an exposure of .1 second gave a good negative, but it was possible to get an adequate negative with a J second or even an J second. Similarly with a x 4 5 objective, 1 second produced a good negative but J second exposure was quite adequate. With the colour film the corresponding values were | second or ,[ second for X 10 objective and 1J or 1 seconds for the x 4 5 objective. In spite of these relatively fast exposure times, some organisms refused to pose and it was therefore found that, as in bird photography, considerable time and patience was needed in finding the specimens and bringing them into focus. However, no organism exhibits perpetual motion and it was usually caught on film by a little ingenuity. The light stops on the camera were not used since as much light as possible was required to reach the film. It was opened as wide as possible (f3.5).
Points for freshwater studies The author's work has been almost entirely with microscopic freshwater organisms and in this field some further problems have emerged.
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If a drop of pond water is placed on a flat glass slide and covered with a coverslip, in three minutes all the organisms have swelled and burst. This has been found to be due to the heat produced by the microscope lamp, but the use of a hollowed slide has solved the problem. For low power work, putting about 10 c.c's. of pond water and debris into a shallow flat bottomed dish and placing this on the microscope platform, provides abundant photographic material in something resembling its natural habitat. Discussion Frink* states that a binocular eye-piece gives less light to one eye-piece than a monocular or triocular model. This is probably true, but for the majority of subjects, whether motile or not, the quoted exposures should be adequate. Frink also states that the camera lens takes no part in the focussing of the picture, so that if it is removable it should be taken out. If left in it should be set at infinity. Conclusion Basically, then, successful photomicrography involves little more than arranging a camera over the eye-piece, choosing an exposure and pressing the shutter-button (which incidentally should be d o n e with a flexible wire release, to a v o i d V i b r a t i o n ) . A little ingenuity should solve the problem of how to suspend the camera. One method has been described.
*Frink D . A. (1961) " Simple directions for photomicrography." Amer. J. of Clinical Pathology 36 : 369 and T e c h n . Bull. Regist. Medical T e c h . 31 : 145-148.