Toronto. It is said that the more things change, the more they are the same. Like the Zeiss Sonnar lens for example. Larry Gubas in his massive text “Zeiss and Photography” shows the Sonnar as it was initially sold in 1932 and the more modern version in 2007. The initials ZM mean that the lens will fit a Leica M-mount (ZM is Zeiss M).
Larry writes, “To the left is a pictorial comparison between the 1932 and 2007 f/1.5 Sonnar 50 mm lenses. They are remarkably similar for being more than 75 years apart”. Elsewhere he notes that the normal lens for the Contarex was the f/2 50mm Planar or f/1.4 55 (58) mm Planar and not the far more popular Sonnar design from the days of the Contax.
The name “Planar” was coined by Dr Rudolph in the late 1890s for his “double-Gauss” lens design. It surfaced once again in the late 1950s as the normal lens for the Contarex SLR. The old Planar design was changed to a modified double-guass design to make the lens “retro focus” allowing it to stay in front of the mirror even at infinity. My Exakta uses a beautiful f/1.8 58mm Steinheil lens for the same reason. My 28mm Angenieux lens does the same with horrible geometric distortion. The Contarex SLR uses an even wider 21mm lens BUT with the mirror locked up and a separate viewer. Note: Much of the Planar data is from Kingslake’s “A History of the Photographic Lens”. Rudolf Kingslake was a Londoner by birth. He emmigrated to the States to teach at Rochester University and head up Kodak’s lens design department.