AFAIK the biggest hurtle is the design of the optics itself -- a 35mm lens focuses light on a different plane than that used with digital. OTOH, the price of 35mm SLRs, especially used bodies has come down a bit. If you could fit your lenses on another body, might be able to also find a digital adapter for it -- I think there were quite a few sold for Nikon for example before pro level digitals came on the market.

Whether it's worth it or not I have no idea... A lens can deteriorate with time, especially in an ozone intense environ that'll eat the seals.

mikkie,
The lenses were produced in the mid-eighties. They will go on several makes of (Japanese) Contax and Yashica bodies. Contax did get around to making one digital model - I think it sells for around 7000 dollars. I have not heard of digital adapters for the Contax/Yashica line of bodies.

nolonemo,
Thanks for the tip. The question had already been asked (and answered) at dpreview. Seems reassuring. I mean, some guy even talked about buying Contax/Zeiss lenses to use on his Canon this way. I think each of my lenses cost me more than a decent Canon EOS body does today. I suppose that little adapter will let me use the Contax bellows too with a Canon.
Anyway, I think I have found the route. Now it's a question of finding the right Canon EOS.
Thanks both of you for responding to a rather narrow thread.
Tor

The Laws of Physics apply to whether it's a Canon or a contax. As long as the adapter has set the focal distance properly, and the resolving power of the glass matches the receptor site pixel size, you will get an image of quality. As you said, the shutter speed and aperture will need to be set manually. In cases where there is a powered optic in the adapter(and this is pretty much needed most of the time)there are losses in both light and resolving power of the adapter optic. It's not uncommon for the loss in resolving power to overwhelm the otherwise exceptional image coming from your expensive lens.

The problem is not really the different plan, its that digital sensors (with the microlenses and antialiasing stuff in front of them) don't accept off-axis light rays as well as film does. In practice, I think, because of sensor crop factor, only an issue with ultrawide lenses.

I have the same camera and lens set and it's a first class combination. Same issue too, but I'm thinking that I'm better continuing to shoot transparencies for dedicated stills work and buy a high quality slide/negative scanner. However on video shoots I like to take digital stills where they might be useful (e.g. a building) and there I really want something that slips in a pocket. Presently I use a little 4 M pix Casio, but it greatly resists being set manually. Something in the 6M class would seem adequate and just as portable.
However I know various dedicated stills photographers who've given away their Hasselblads for 12 Mpix digital SLRs, so I'm probably wrong in wanting to keep using those Zeiss lenses! As an aside, setting manually is what we always did so I wouldn't think that a problem of concern.

Bill Ravens,
There are no glass in this adapter. It is just a "ring" that adjusts distance while fitting one type of bayonet to another. There are at least three different makes. One difference is that two of them uses a tiny set screw. This makes it impractical to use one adapter for several lenses. But then they are a little cheaper. The third (the one at cameraquest) has a locking latch, making it faster to change around.

I know very little about how light travels through a lens and hits a receptor at the back of a camera house. But some people seem to be happy using such very good lenses on digital Canon bodies - meaning they prefer this to the available Canon lenses (which, from what I hear, can be quite good, too). That is all I know.

Serena
You have a choice. My Contax 159 MM is not working because of what appears to be a known issue - something to do with the exposure electronics. A repair shop in Oslo charged me $ 100 to say it would be outrageously expensive to fix it. So I have these fine lenses on a shelf - unused for maybe 7 or 8 years. I also have bellows and dias duplicator. (I wonder how that competes with a film scanner.)
Besides, I want digital. Otherwise I suppose I could have picked up a used Contax or Yashica body somewhere. I'll be happy with 6 or 8 M though.
It is the only time in 20 years I have come across someone with the same camera and lens set. Amazing.
Tor

TorS
You're right about Contax digital backs I think - thought perhaps there might be something around from around 2000, but a quick look didn't seem encouraging at all. Contax did make a digital SLR that accepted previous lenses, but it was a marketing failure. Still, might be worth looking into I suppose as used prices might be reasonable -- but only *if* you could live with the faults of the camera. FWIW nowdays the focus re: digital backs seems to be on medium format cameras, in the price range that you'd rent rather then buy.

I do suggest posting in a few photography forums before buying anything though. You might find you'd be better off spending the money on new camera gear rather than adapters. It would be easier if you could compare your own lenses with current products, but don't know how you'd do that without spending the money 1st -- maybe by posting elsewhere you'll find someone who has done it.