Schneider Curtar 4/35 vs. 5.6/35

[BrianShaw]

Does anyone know the difference -- design or quality or anything-else -- between the C-mount (Kodak Retina RF) Schneider Curtars. What I now know is that one is f/5.6 and the other is f/4. The f/4 is much larger, but other than that I'm clueless. Any information will be sincerely appreciated!

[BrianShaw]

Okay, I found part of the answer:

The two lenses seem to share a similar design: 9 elements in 6 groups (including the common rear element). Both of the 35mm front lenses have 6 elements in 4 groups. Perhaps the biggest difference is the physical size -- the f/4 lens being about twice the size of the f/5.6 lens.

But... what about image qualities... is one better than the other?