This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Focusing. With the camera placed on an exact line with the microscopic slide and the bellows extended, you can obtain the focus by racking the bellows of the camera to and from the object. Should the image not be sufficiently large, you obtain a larger image by sliding the camera closer to the object and extending the bellows longer. The largest image that you can obtain will depend on the focal-length of your camera.
Stopping. As good sharp detail is required, the lens should be stopped down at least to F. 32, and in some cases still smaller openings should be employed. The same plates should be used for this class of work as you would use when photographing with a microscope, for the same values must be retained. For all ordinary work the regular lantern-slide plate may be used. For special work, where the relative color values are of importance, the slow orthochromatic plate will be found an improvement.
Dissecting Subjects For Photo-Micrography. Some subjects (such as flowers) must be dissected. Fig. 2 of Illustration No. 126, page 352, shows the method of using the microscope for this operation. Some difficulty may a first confront the student, owing to the object being inverted, as the work will be performed opposite to that naturally done without a microscope. The slides for dissection are made by flowing them with a thick liquid solution of gum arabic and allowing to dry. By breathing upon the dry slide it will become sticky enough to make the subject adhere for dissection. The 2/3 objective is mostly used, as there is a good working space between objective and slide.
Printing And Finishing. The making of prints from photo-micrograph negatives is usually done on glossy printing-out paper, or on glossy developing (gaslight) paper. Generally, the latter is employed, as it is the most convenient to use and quicker results are obtained, and for the busy man this is quite important. Another convenience, especially where artificial light is used for making the negatives, lies in the fact that the same illuminant may be employed for making the prints. For the manipulation of the different printing papers, see Vol. IV.