[The Zeiss ZM 15/2.8 Distagon for Zeiss IKON or Leica M is an entirely different lens from the the new Zeiss ZF.2 / ZE 15mm f/2.8 Distagon for Nikon and Canon]
Paul R writes:
You and your wonderful website have been instrumental in my move to Leica.
For your information, and that of your readers, I have found a way to use the wonderful Zeiss ZM F/2.8 15mm lens without its central filter, and still get great results. This involves CornerFix and Adobe lens corrections, and is covered in Section 7 of my new article.
DIGLLOYD: The Zeiss ZM 15mm f/2.8 Distagon ships with a center filter that reduces light transmission by ~1.5 stops, resulting in a T-stop of ~T/4.8 (probably a little slower in actually, since lens itself is probably T/2.9 or so.
While one can shoot without the center filter, the additional 1.5 stop differential can mean noisier corners, since they will be exposed by 1.5 stops less than with the center filter.