It depends a lot on the individual glass. Not all of them are so great, and even less actually are worth spending 2-3 times as much as for the competitors. It's really more a matter of having an exclusive lens than of a real optical need.
True, but 100F2 & 25F2 are really outstanding. IMO, 100F2 is the poor man's EF 200F2.
Ha! I really love the Zeiss 100mm f/2, but at a price point of 1600€ it's hard to find reasons to buy it. Canon 100mm f/2 and 100mm f/2.8 L IS macro are great lenses and you can buy both while still sparing 300€ over the Zeiss, not to mention the AF.
The same is true for non-Canon users. Consider that the Zeiss is only a 1:2 macro, so more a portrait lens than a true macro. Within this scope, 85 or 100mm makes a little difference, and the Nikon and Sigma alternatives in this range are quite good, AF-equipped and extremely
why does it make more sense to canon than nikon? canon has some outstanding glass
Canon is unbeatable in the 100+mm range, below that, even L-lenses lose to the competition. Moreover, if you want at least focus confirmation on Canon you have to buy Zeiss, while on Nikon you can have it also with the much cheaper Samyang and Voigtländer lenses, just to mention a couple.