Part of the Zeiss Jena holy trinity IMO - Flek 35, Pancolar 50 and Sonnar 135. Get a good copy of the Flek 35 and it'll make a superb walk-around lens that even does close-focus as you can see above.
I have Distagon 35/f2.8 MM as well as Flektogon 35/f2.5.
Distagon is an excellent lens but I prefer Flektogon for its rich colours and close focusing.
It is my all time fav lens. No problem on 5D.
Is there any advice on getting one of these? I have seen pictures and the writing on the lens looks different based on (i'm assuming age of the lens) Is this true?
The 35 2.8 Flek is one of the best 35's I have ever used on any camera. Used it on my 5D and now I use it on my Sony a900. I have tested mine against a C/Y 35-70, an older German Zeiss Rollei 35 2.8 and the classic Nikkor 35 F2. The only lens which is ever so slightly sharper into the corners is the Rollei. The C/Y 35-70 is an amazing lens but vignettes severely until stopped down to F8/F11. It also suffers much worse distortion than any of the fixed 35'5.
This lens has one major fault which is the aperture mechanism. Eventually, it is fairly common for it to start sticking. Fortunately, it is an easy lens to disassemble and the fix is a simple cleaning/soaking of the mechanism.