I have never used the Kowa, and just going by the retail price, it seems only logical that the Zeiss Terra is a better device (it's way more expensive, at least in Europe), but here's one thing to consider. Unless you definitely need the folding ability of the Terra, the dual hinge is a bit of a nuisance, and the single hinge on the Kowa will probably make it easier to use, more natural, like any other "conventional" pair. After trying several double hinge models, I just think the single hinge is way superior in terms of comfort and ease of use (but that's probably just me).