Archived posting to the Leica Users Group, 2001/04/01

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Subject: RE: [Leica] Re: ken's 15mm heliar
From: "Frank Filippone" <>
Date: Sun, 1 Apr 2001 17:49:17 -0700

Light falloff can and has been corrected several ways.....

Firstly, through design.  The Bioigon design shows little to no falloff in
the corners, wheras the Super Angulon shows much falloff.

Secondly through ND filtration to compensate for the fallof, ala Center
filters made for SA Lenses.

Third, through a special filter used on the Metrogon lenses where there is a
pattern in the filter, that looks like a multi rayed propellor.

Finally, in the Goerz Hypergon Lens, there is employed a real propellor that
spins around and "filters" the center more than the eriphery of the lens,
evening out the illumination.

Frank Filippone