MICROPHOTO — the photographic shooting of microscopic objects which is carried out by means of a microscope or special microphotos of graphic devices.
The m is applied for documentation and demonstration of the results received with the help microscopic methods of a research (see). At M. the low-format mirror camera the camera without lens is strengthened on an ocular tubus end of a microscope by means of transitional and lengthening rings. Aiming on sharpness is made by a micrometer screw microscope (see) it is also controlled on ground glass of the camera.
For M. it should be established by the low-format camera with not unscrewed lens on infinity and to completely open a diaphragm. After focusing of the image seen in a microscope bring a lens of the camera to its eyepiece and make shooting. Because the rays of light passing through an eyepiece are close to parallel, the lens of the camera focused on infinity has the sufficient depth of sharpness. Increase at this type of shooting is defined: fV = V o6 * V ok * (f/250), where V — total magnification, V about — objective magnification, V ok — the increase in an eyepiece specified on its frame, f — focal length of a lens of the camera (mm).
M at small increases sometimes make with use only of a lens of a microscope, to-ry carries out in this case a role of a lens of the camera. Increase at the same time is counted on a formula V = To / f' where To — distance from the center of a lens to a photolayer (mm), f' — focal length of a lens of a microscope (mm).
Most M. by means of photomicrographic attachments was widely adopted. For M. nozzle ocular cameras are used to plates (MFN-1) and to a film (MFN-3 and MFN-11). The nozzle camera is installed on a microscope and rigidly connect to it (fig.). In such microphotographic device the projective system is in a special tube, to Krom the nozzle with a vizirny tube fastens. The svetootdelitelny prism sending a part of incident light to an eyepiece of a viewfinder, and a part — on the plane of the image so in an eyepiece of a vizirny tube the same image, as in an eyepiece of a microscope is visible is installed in the case of a nozzle. The nozzle camera can reside in the working position on a replaceable tube of a microscope. Blowup of an object is determined by a formula:
V = V o6 * V ok * (K/250)
where To — distance from an eyepiece to a photolayer (mm).
In practice widely apply the stationary microphotographic installations (MBI-6, MBI-12 and MBI-15) consisting of a microscope, the camera and lighting system. These installations are constantly ready to M., their lighting equipment of a sjyustirovan concerning a microscope, and a microscope sjyustirovan concerning the camera. The built-in exposure meter and combination of an observed picture with the plane of the image in the camera create the maximum conveniences to M. In microscopes of MBI-12, MBI-15 photographing is made on a film with sizes of shot of 24 X 36 mm or plates the sizes of 9 X 12 cm.
High quality of microphotos manages to be received by means of apochromatic lenses, special photographic eyepieces and eyepieces like gomal. At M. with small and medium increases it is reasonable to use achromatic lenses, Huygens's eyepieces and compensating oculars. Are most effective in M. the plan lenses with achromatic and apochromatic correction since with their help the image of flat objects is uniform on a bigger extent.
Depending on coloring of a dischargeable object at M. use the light filters installed. between the lighter and a microscope, the conditions for good reproduction of details of an object eliminating residual chromatism of lenses and creating. Light filters, coloring apply to identification of details of intensively painted object to-rykh it is close to coloring of an object; at M. of pale-stained preparations use the light filter supplementing coloring of drug. During the work with achromatic lenses it is not necessary to use blue and red filters; apochromatic lenses allow to use all set of light filters.
Lighting at M. shall be intensive and uniform on all field of microscope. Light rays concentrate optical system of a microscope on the small area of a shot of the low-format camera therefore the image has sufficient brightness even at the low power of a light source, napr, the ordinary OI-7 or OI-19 microscope lamp. At M. on small increase illumination of the field can be increased due to removal of an upper (frontal) lens of a substage condenser or replacement of the condenser with a photolens with focal length of 50 mm and a relative opening 1:2. It is possible to increase contrast and sharpness of the image by diaphragming of the condenser under direct vision through an eyepiece of a microscope.
The endurance at M. depends on increase, density and coloring of drug, sensitivity of a film, the used light filter, the condenser, etc. Determination of endurance can be made by preliminary exhibiting of a number of shots with the changing endurance, and also by means of special exposure meters, e.g. EFEN-1. M. with various exposition devices, napr, with a phototimer of mf-matic of production of GDR has big advantages. The main unit of such device contains the special electromagnetic lock managed by means of the switching device and allowing to automate complex process of the choice of exposure.
For black-and-white M. usually use the film of MZ-2 having big resolving power and the increased contrast, and also films «Photo-32», KN-1, to-rye are sensitive to all beams of a visible range and allow use of various light filters. At M. of the pale-painted or colourless microscopic drugs it is recommended to apply a contrast film like Mikrat; good results are also yielded by use of special photographic plates («For the scientific purposes», «Micro»).
At color M. establishment of compliance of spectral structure of a source of lighting to features of reproduction of color on a film is of great importance. Setup of the mode of lighting for this purpose can be carried out on a so-called gray scale, to-ruyu make by fogging of black-and-white matte photographic paper to receive on it various shades of gray and black color. Samples of the photographic paper prepared thus paste on a cardboard in the form of a circle and make a copy on a positive film. The received test scale to dia. 6 — 8 mm establish on a slide plate in sight of a microscope and make a copy of it on a color film with various combinations of light filters. The rational mode of lighting corresponds to a shot, on Krom the scale has neutral-gray color. Apply apochromatic lenses, photoeyepieces or eyepieces to color M. like gomal. Color M. without light filters is made on a negative film of LN-3; use of a film of the DS-3 type using purple and blue correctional light filters, a reversible film like TsO, etc.
See also is possible the Photo in medicine .
Bibliography: Sabot of. The color medical microphoto, the lane with Wenger., Budapest, 1967; Fedin L. A. and B and r-with to and y I. A. Microphoto, L., 1971, bibliogr.; Sh e p E. G. Use of the photo in medicine, M., 1974, bibliogr.; Bergner J. u. a. Praktische Mikrofo-tografie, Lpz., 1973, Bibliogr.; Lawson D. Photomicrography, L., 1972.
H. K. Permyakov, G. M. Mogilevsky.