Archived posting to the Leica Users Group, 1996/10/10[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
Leitz originally marked the aperture on its lenses in the 'Continental' or Stolze sequence (f/1.1, 1.6, 2.2, 3.3, 4.5, 6.3, 9, 12.5, 18, 25, 36). After World War II, they phased this out and replaced the Stolze sequence with the 'Universal' or 'International' scale we know today (1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32). I would suspect all M lenses use the International scale, though vestiges of the earlier usage persist in the maximum aperture of the 3.5/35, 3.5/50, and 4.5/135 lenses). The Stolze-scale lenses opened to f/36 for the 9cm Elmar and 13.5cm Hektor lenses, and this was changed to f/32 when production shifted to the Universal scale. On the other hand, normal lenses were limited by diffraction effects, especially in pre-coating days, to a larger minimum aperture: the 1.5/50 Xenon only going to f/9 and all of the 3.5/50 lenses only stopping to f/18 until the International Scale was adopted. Both of my collapsible 90mm Elmars open to f/32 as does the rigid lenshead I use on my Bellows. Marc email@example.com FAX: +540/343-7315 Cha robh bas fir gun ghras fir!