[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Rollei] Re: Why the 6-element lens for 3.5Fs
- Subject: [Rollei] Re: Why the 6-element lens for 3.5Fs
- From: Eric Goldstein <egoldste >
- Date: Wed, 30 Apr 2003 19:37:44 -0400
Richard Knoppow wrote:
> Since some report good performance from these CZJ Tessars
> the design was not the problem. In general Tessars are not
> at their best at f/2.8 but can be quite satisfactory.
In his book "Photographic Optics," (1950) Allen R. Greenleaf states that
Tessar designs are optimal as f/6.3 lenses, and no matter how carefully
designed and constructed, versions faster than f/3.5-4.5ish "would not
satisfy a critical user." (Mr. G himself seems like quite the critical
Today, even with modern glass, design and fabrication, Tessars of f/2.8
speed are produced for miniature use only...