Why there isn't an F/1 Sonnar?

awilder said:
Among the fastest lenses for 35 mm cameras are the 50/0.95, 50/1, 50/1.2 Noctilux's and are all forms of the Xenon/Planar designs with enhanced performance by incorporating exotic glass, aspherics or both. Nikon's and CV 50/1.1 are Xenon variants. Konica RF 50 or 60 mm f/1.2 are also Xenon designs but with improved glass. Canon's 50/0.95 or 50/1.2 is also a Xenon/Planar design without exotic glass or aspherics. Zeiss made an anniversary edition 55 f/1.2 for their Contax SLR seen here: http://www.geocities.com/ilprode/_55f12.htm. Speeds faster than f/1.4 result in an exponential increase in nasty high order aberrations necessitating the expensive additions of aspherics and exotic glass for decent performance. The RF 50 Sonnar design is stretched to it's limit at about f/1.4 and Nikon RF's wisely redesigned it as a much improved Xenon derivative known as the Olypmic version in the early 60's. This lens design was repeated with the reissue of the S3 in 2000 and is competative with the very expensive 50/1.4 ASPH. Summilux M.
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I once did some 50mm lens comparisons, and among many other lenses, there was a Canon 50mm/0.95 and its "slow" cousin the Canon 50mm/1.2. plus a Noctilux 50mm/1.0 and a Nikkor 50mm/1.1.
 
Aha! Found this on the Zeiss site:

5. What is the fastest camera lens that Carl Zeiss ever built?
The 50 mm Planar f/0.7 lens. It was created for NASA to take pictures of the dark side of the moon. It was also used for movie-making.
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