On the left is the Schneider Componon 4/28 at full aperture at f/4, and on the right, is the same lens cells in a different iris housing, this time wide-open at f/2.
Componon 28mm f/2 Iris Upgrade
The CPN 4/28 test page has been updated with some new information. One thing I added was another way to upgrade the 4/28 lens iris to f/2. Instead of opening the lens and modifying the iris tab, the new method is a lot easier. The new method is simple and involves simply swapping the front and rear lens cells to a new iris housing.
Follow this link to see all the test updates: https://www.closeuphotography.com/schneider-28mm-f4-lens-test