As a tangent on the Zeiss 21mm story, Canon shooters will be glad to hear that the 24mm f/1.4L holds its own quite well against the Contax MM 21.
The reviewer’s syntax is sometimes quirky but he cracked me up with this one:
…we know the outcome in broad terms before we begin: the Canon will be punished by this comparison – what we're looking for is an honourable accounting of itself in the face of insuperable opposition.
Honestly though the 24L impresses quite a lot, it doesn’t get punished very hard. Not only is it better than the Zeiss 21mm at all common apertures below f/8 but it starts out the door with a 2-stop lead. Quality at 1.4 or 2 isn’t stellar, but hey it’s there. As compared to all the other 21-24-ish lenses, including the zooms, these two (+ the Nikkor 14-24) are very close to perfection stopped-down. I suspect the Nikkor 24mm PC-E is the fourth musketeer.
At ~$1200 at B&H and Adorama the 24L is pricey but completely in line with its competition and is a fair value. Particularly among the four lenses mentioned above, it is the least expensive by a wide margin however.
As I’m building a prime-only kit myself, I’m a bit jealous of Canon shooters on this one. These guys get to use the Contax MM 21 on adapters, or buy the 24 1.4L natively. The Nikkor PC-E is certainly an option for me, but the price is a bit of a turn off. I’m personally waiting to see what 21mm Zeiss ships on the ZF bayonet…