Re: Realist lens-Wm Carter (digest 1525)

[P3D Bob Howard <bobh@xxxxxxxxxxxxxxxxxxxx>]

RE: William Carter with some odd out of focus effect asks if Realist
lens has "field flatener", not rear element. This is not so easy to
answer as any lens that is providing a Petval correction to get a flat
field might be called that and it might be the rear element? But in the
normal triplet (Cooke type) or Teasar (a triplet with compound read
element) there is nothing called a field flattener. This tern used
mostly on movie projection lenses..which are often called Petzval
design. (I think he computed the first lens for Voightlander in Vienna
than was design by mathematics for daguerotype?) BobH


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