Firstly I should declare that I am a big fan for the chrome lenses!
For chrome 50/2 and 35/4, they are having a closer minimum focusing distance then the blitz black one........
The damping feeling for the focusing barrel of the chrome lenses are also generally better than the black lenses from the Contarex lenses I do own now..........
Generally I do feel that the chrome lens feels more solid with better craftmanship than the black lenses, especially when compare with the later production with serial no. greater than Nr. 45xxxxx something..............you can see the downgraded engravings on the lens barrel as compared with the early chrome lenses. The material for the lens barrel on the black lenses are just plain flat black anodized aluminium, while the chrome lenses are beautifully finished with very fine and even "凹凸" pattern to improve its hand feeling rather than a plain surface
The myth of black lenses to be better than chrome lenses, personally I do realize that it is a matter of coating changes leading to the difference in colour rendering characteristics, just like "White Face" Rolleiflex 2.8F comparing with the earlier version. I got on my hand two Planar 50/2 with serial no. 237xxxx and 480xxx, one can easily distinguish them from their "golden" coating to the "purple golden" coating (just as the coating changes on the Planar 80/2.8 on the 2.8F), which gives a slightly higher contrast and saturation to the photo which appears to be more attractive to the eyes for most people.........
Personally I suppose we should rely on the serial no. rather than just black or chrome lenses for identifying the "characteristic" of certain Carl Zeiss lenses for Contarex (may be for Hasselblad as well
). I had closely examined my chrome Distagon 25/2.8 (with serial no. 356xxxx) with another black lenses with serial no. 397xxxx and actually I do not able to find any difference even for the coating colours, as a counter case to the Planar 50/2 as mentioned above. In my own opinion, chrome lenses with serial no. around 35xxxx should be the best to get (with serial no. ususally started with 36xxxxx), in which they are having the craftmanship of the "chrome lenses", while with the characteristic very much like the "black lenses", and most importantly, priced like chrome lenses
Reference Material -
Contaxflex and Contarex, Hans-Jurgen Kuc
ZEISS Compendium, Charles M. Barringer and Marc James Small
P.S. Here is another very special example from ebay
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7532352363&category=707&rd=1
This black Distagon 25/2.8 is having a serial no. 258xxxx, in which the initial 258 may refer to as a prototype lens
(with reference from Hasselblad Compendium, Richard Nordin, Page 274)