Leitax now makes Canon adapters for the Contax lenses. The Leitax adapters reuse the original lens screw holes and the Leitax adapter is actually screwed to the lens. I had Leitax adapters with my Leica R lenses and I was very impressed with the quality of the Leitax adapter - a full review is available here. For the Contax 35-135mm Sonnar-Vario, I strongly recommend looking into the Leitax Contax/Canon adapter. I purchased a couple of the Leitax adapters and now use them on the Contax 35-135mm and Contax 100mm F2 Planar. After a year of use they are still doing great and I feel much more confident with them.

I am always a bit hesitant to take the Contax 35-135mm on vacation because I know focusing at the 135mm can have a low keeper rate. But, I always enjoy using this lens. The processed images look great and Contax build quality is sublime. If Zeiss were to re-issue the Contax 35-135mm and new Zeiss ZE dress, I am sure the price tag would be $2000 or more. If you consider your a true Contax fanboy, you owe it to yourself to at least try the Contax 35-135mm. Used prices are pretty cheap and they can be easily found Ebay.