Archived posting to the Leica Users Group, 1997/02/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 08:37 AM 2/7/97 +0800, Dan Khong, man of import and depth, wrote: >The aperture progression is in Stolze? units - the fun starts when you try to set >modern aperture readings onto the 90 Elmar. The Stolze scale is the older 'European' aperture scale -- f/1.1 to f/100 in doubling apertures -- which was later replaced by the 'International' or 'American' scale popularized, ironically, by Carl Zeiss. Thanks to Eric Welch -- of lamented memory to many of us -- I obtained, for the princely sum of $25, one of the only two known Carl Zeiss Jena lenses marked in the Stolze scale, and the sucker dates from 1910. Leitz continued to mark its lenses in the Stolze scale through the Second War and, even afterwards, the scale left its imprint on the Elmar and Hektor designs. In any event, from a user angle, it's no sweat, as the Stolze scale markings fall at the half-aperture points of the International scale. Thus, half-way between f/4 and f/5.6 is -- lo, and behold! -- f/4.5. These are geometric scales, and the progressions are based upon squares and square roots. Marc msmall@roanoke.infi.net FAX: +540/343-7315 Cha robh bas fir gun ghras fir!