Just looking for a reasonable cost Contax-mount super-wide for the Ultimate or Extreme. I just can't afford the Zeiss C/Y 21mm. There are others like Cosina 20mm 3.8 but I've read that it is very soft wide open. Is anyone using the Zeiss 18mm F4 on a Letus?

Cheers,
Peter

I use one, but not on a Letus.
It's a nice lens to have in the kit. A little slow, but but still very usable.

Here is a shot with available light, and the lens wide open.