![]() ![]() ![]() ![]() Screwing the lens up and down permits the lens to be focused to suit the user.' The notation suggests this was not officially marketed as a fingerprint magnifier until after the 1935 catalog. The lens is 1 3/ 8" in diamter and mounted in a threaded ring which fits into the horse shoe base. ' We have designed a 4 1/ 2 power magnifier, which is mounted on a horse shoe base and fully corrected for chromatic aberration, flatness of field, astigmatism, and distortion when the eye is held from 4 to 5 inches from the lens. As can be seen in the image of an engraving taken through the lens, the entire field is sharp and flat. The instrument shown here also has a locking ring to lock it in focus this additional feature is advertised as a separate accessory to add to the functionality of the device. The earlier version of this instrument, shown here, has a gloss black finish the later version, shown next, has a flat crinkle finish. Note that at the bottom of the instrument there is a dovetail slot in the horse shoe foot to accept inserts with a ball-bearing under one side of the foot to hold the insert in place. The use of the postal code dates it to after 1940. Although all of its advantages were mentioned, it was not specifically promoted as a fingerprint magnifier initially the box with this instrument does list it as a 'Fingerprint Magnifier' and is identical to the box for the next instrument on this page. Both B & L and Spencer called these magnifiers 'Utility Magnifier' without the slot in the foot to accept the Henry inserts, and 'Fingerprint Magnifier' when the slot was present.īAUSCH & LOMB 4 1/ 2 power magnifier on horseshoe base: Bausch & Lomb advertised this magnifier no later than the second quarter of the twentieth century. Magnifiers with lenses nearly identical to these are still sold today by companies specializing in forensic tools, but the quality of the B & L and Spencer models on this page were never surpassed. Obviously these instruments were well suited to other purposes. Such magnifiers were available in the early twentieth century and soon were promoted for the purpose. An achromatic aplanatic lens combination with large aperture and good eye relief would fit this requirement. Ideally a magnifier for examining finger prints should provide a sharply focused and flat wide field with a magnification of about 4 1/ 2 X and avoid the need to be close to the lens so as to limit fatigue. FINGERPRINT MAGNIFIERS: SECOND TO THIRD QUARTER OF TWENTIETH CENTURY DESCRIPTION ![]()
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