I am seriously considering the above 2 lenses and I am torn between the 2. I do not intend to get both at this time --- just one. Both are Biogons and the used SWC is about the same price as the new ZM 21mm. I am not using these for architectural work but more likely humans, night citiscapes and may be landscapes. I lust for big prints so there's my problem: the SWC gives me a 6x6cm but not as portable and the lens is a lot slower than the ZM. Anyone know if camera shakes is big problem for the SWC and is it, primarily, a tripod bound camera?