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Folding Portable Compound Microscope




c. 1930


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minorminorThis is a well made, folding, highly portable microscope from the 2nd quarter of the twentieth century. It is signed 'Ernst Leitz, Wetzlar, No 286794'. It arises from a horseshoe foot to an inclination joint. There is a swiveling substage mirror which is concave and can be brought around to the top of the stage for illumination of opaque objects. Under the stage is a miniature detachable Abbe condenser with iris diaphragm and clips to accommodate a substage filter. The condenser is threaded to screw into the the hole in the stage. There are two removable stage clips. Coarse focus is by push-pull and fine is by a knurled ring just above the arm which moves the sleeve holding the main tube. There is a draw tube. The main objective assembly provides two powers with the higher power achieved by turning the knurled knob to bring an extra bottom lens into place.

minor demo modeThe objective assembly can be exchanged for a special low power objective which, after removal of the condenser, allows inspection of a solid surface through the foot; it can also be used for low power views of slides, using the foot as an accessory stage with the stage clips moved to the foot, which has holes to accommodate the stage clips. For low power views of transparent objects placed on the foot, illumination would be by holding the instrument up towards a light source. Another way to use this microscope is as a demonstration microscope, with a slide on the stage, using the folded foot as a handle. With the low power objective attached and the foot and pillar as a handle, it could also be used as a handheld microscope to observe stationary subjects, as shown in the illustration on the front page of a Leitz Brochure, which can be seen at the bottom of this web page. As shown in the image to the left, its foot and upright can be used as a handle to pass around the instrument as a 'Demonstration Microscope.' When used as a demonstration instrument, each user would hold it up to the eye with the understage pointed towards a room light or window.   Additional accessories include a choice of blue filter or a ground glass, to be placed under the condenser, using the clips on the bottom of the condenser provided for the purpose. There is a leather carrying case. The case does not have a belt loop. The biggest defects of this design are that it is relatively light and that the horseshoe support is just not wide enough to prevent tipping the scope right or left. It provides very low to moderate power; it always lacked an oil immersion high power objective. In my example, I do note slight image shift when using the fine focus.

Minor Microscope To fold up the microscope for storage, first the tube and draw tube are pushed all the way towards the stage. Then the foot is folded back on the pillar. The mirror stem then is raised up parallel with the body tube. Then the pillar, (with the foot folded on top of it), is then folded backward on the inclination joint.

mag tableThe table, from the 1929 catalog, shows the range of magnification and working distances for this instrument.


1924 minor entry1929 Leitz Minor cat entry High quality portable microscopes became popular during the 1920's, and the Leitz Minor was one of the best of these. In 1924 it was offered only as one model without a condenser, but by 1929, it could be ordered with the removable substage condenser seen here, and called the 'Minor 2'.

Additional polarized light accessories were available for converting the Minor into a pol scope. These included a complete selection of petrographic accessories in two different kits. The 'Minor 5, Mineralogical Accessories includes an attachable rotary stage with vernier and centering screws, an attachable polarizer and analyzer (with the analyzer in a swing-out mount). The 'Minor 6, Auxilliary Equipment to Mineralogical Accessories' was listed to include a Bertrand lens to thread onto the oculars, a 30X objective, a two-lens condenser for the polarizer, and a set of eight selenites and mica plates to be 'placed upon the ocular'. Fully equipped with all of these, this may be the most complete miniature petrographic microscope ever made. The Mineralogical accessories kit is rarely seen and Dan Kile reports seeing less than 7 examples. He also reports that the Auxiliary Equipment set, (with the Bertrand lens), is virtually nonexistent, as no surviving example has thus far(2020), been identified.

The Leitz Minor was apparently made from about 1924 through at least 1934, but did not appear in the 1938 catalog. According to Dan Kile, about 31 or so examples of the Minor are known to still exist, and serial numbers range from 225725 to 311867. It was rather expensive in its day, but the optics of this instrument are superb. It was meant to be a highly portable instrument for the serious microscopist, much like the inverted McArthur microscopes which became popular in the third and fourth quarter of the twentieth century. 1924 minor entry