The biggest reason manufacturers went to more elements for super-teles
after coating was developed was to reduce the size of the lenses using
retrofocus designs that require several elements. The Zuiko 600/6.5, for
example is 377mm long. that plus the ~45mm register distance gives a
total of 422mm, so the virtual focal point is about 175mm in front of
the front of the physical lens. A doublet design would be about 550mm
long, 460nger! Improvements in correction were possible as well, but
were secondary to the enormous decrease in size.
Moose
Bill Stanke wrote:
"A cemented doublet telescope objective gives excellent definition over a
semi-field of 2 or 3 degrees; therefore this simple system can be used in
lenses of 400 mm or longer focal length for a 35 mm camera. The length of
the tube from lens to film is, of course equal to the focal length.
However, the lens is very light in weight and gives excellent definition at
apertures of f/5.6 or smaller."
Granted, this is a longer focal length, but if E. Leitz thought two elements
were the right number, then I won't quarrel with them.
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