Form Stephen Gandy's website at:
"90/2.8 Tele-Elmarit 1974-1989 "thin" version This smaller Tele-Elmarit version has the honor of being the smallest and lightest 90/2.8 ever made for the M Leica. Amazingly, despite being one stop faster, it is virtually the same size as the 90/4 Elmar made for the Leica CL. It is an outstanding choice as a travel lens. While some have complained about its sharpness, others have praised it. Modern Photography rated it sharper than the 90/2 Summicron--something of a surprise to many photogs.
This version has a chronic problem to look out for which shows up in my experience about 5% of the time. For reasons unknown, it can develop a severe etching of the rear element. The problem can be stopped in the early stages by a professional cleaning of the lens elements. If it has proceeded too far, however, cleaning will do no good and the damage is permanent. Unfortunately this turns the Tele into a nice paperweight, since the rear elements of this particular lens are a sealed unit -- making it too expensive to replace even if you could find the elements.
I long believed the problem was the result of animal based lubrication attacking the glass. I had my Tele relubed to alleviate the problem -- and it hasn't shown up. Mr. Horst Braun, the Manager of the Leica repair department, firmly believes this is not true, since the same lubricant used in Tele-Elmarit is used in other Leica lenses. He suggest the problem may be a lens fungus...but why it should attack this particular lens design more than others is unexplained. Leica is looking into the problem. "
I got a good copy of this lens from another member here. One of my favourites-a great little lens I expect to put to good use for candid family photos this afternoon at a niece's wedding.
