I have been looking for information about how to take apart my Zeiss Planar 50 mm 1.4 lens to repair the stuck aperture blades for years without success. I have two of this lens. One had oily aperture blades now the aperture is stuck open and the other has broken aperture mechanism inside. One is a MM version and the other is an AE. They look almost identical. I am willing to risk one to try to fix it then apply the knowledge to the other one. For many years I could not find any information about how to take the lens apart. Well, I now found this on the internet: http://forum.mflenses.com/viewtopic,p,1222565.html#1222565 The picture posted in that thread shows the front barrel of the lens (along with the name ring as part of the barrel) removed. It is the part on the left side of the picture. Does anyone know how that front lens barrel is removed or unscrewed? I have tried to unscrew it (by assuming that it is screwed on) it in clockwise and counterclockwise with my bare hands with no success. I can't find a lens wrench of that size (don't know the size either). Does anyone ever worked on this lens? I have contacted a good repair shop and was quoted a price enough to buy a used one. I bought the MM version of mine new and it is still spanking new today. I really like to get it fixed. The AE version one was bought by me as a replacement for the MM one but it broke down only after one year of use. I do not want to try to get another one to yet getting into another broken one. So I want to do it myself. I have fixed a few lenses and cameras and I am quite handy. I just need to find out how to do it and will buy the necessary tools to get it down. Any help will be much appreciated.