In article <4fg0hv$9cb@hpwin055.uksr.hp.com>, bob@hpwina25.uksr.hp.com says...

>joe b. (joe@azurite.demon.co.uk) wrote:
>:| Anyone have any experience of opinions on the Distagon 18mm/f4 for
>:| Contax SLR?

>One of these is on my shopping list, so I've been taking note of tests
>etc. The tests I've seen are very positive - performs as you would
>expect from a Zeiss optic, and in particular very good at controlling
>flare and distortion. Whether its worth the new price is an individual
>decision - I'm still saving for a used one! I have read that the 21mm
>is better, but there again, the 21mm is much newer.

I have never used one, but every one of the few photos that I have seen taken with this very old design (including one in the Contax literature)
has been soft in the corners..... (Warning, this is NOT a definitive
evaluation of this lens! ;-)
Hope This Helps