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construction of the bayonet lens mount, however, a dead spot existed for each lens since the minimum thickness of the adapters was 5/16 in. This was considerably greater than the total focusing excursion of any of the above lenses. In order to overcome this difficulty, we obtained 48-mm and 72-mm MicroTessar lenses and fabricated slip-tube adapters by means of which the lenses could be focused at any film-to-subject distance. These lenses have been used with marked success in microscopic high-speed photographs of individual filaments at magnification ratios up to 5 to 1, field width being less than 1/10 in. The lenses have also been used successfully in macrophotography.
A Sept 35mm camera was purchased and altered to provide a continuously moving film camera which could be used for streak or oscillographic photography. In addition, it has been used in many instances with the StrobotacStrobolux combination for taking motion pictures of action so slow that the use of regular high-speed equipment was thought to be unnecessary. In this connection, it was found that two or more Stroboluxes may be triggered by a single Strobotac and that by using this arrangement satisfactory pictures of many subjects may be taken. Figure 4 is an example of the use of this technique in studying bubble formation.
The operation of bubbling vapors through liquids as a method of accomplishing transfer of either liquid or gas components is a basic operation in many chemical processes. The purpose of the study was to obtain data relative to the effect of bubble rate, gas density and viscosity, liquid density and viscosity, surface tension, hole size, etc. Simultaneous high-speed pictures and dynamic pressure records were taken in many cases.
In addition to the necessarily abbreviated examples presented here of applications of high-speed photography at the du Pont Company's Mechanical Development Laboratory, the technique has been used in the investigation of almost every phase of textile manufacture, from the spinning of a single filament to the sewing of finished fabrics ; in the study of paint spraying; in metallurgical studies; and in the investigation of fundamental chemical processes. It has also been used to study the effect of explosions.
High-speed photography has proved to be a valuable research tool ; however, our many investigations have shown that there is an enormous field which present equipment does not cover. We are looking forward to the time when picture rates many times in excess of what is now possible will be commonplace.
Johnson: Photography in Chemical Industry
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