3rd party lenses and compatibility

[pgseye]

What are peoples experiences with third party lenses they might have bought a few years ago (for Canon bodies) and compatibility with current digital bodies (specifically 350D, 20D).

I am thinking of buying a Tamron lens for a 350D. Does it ever happen where Canon might change/or tweak the firmware of a new body and suddenly it prevents older lenses which used to work with Canon bodies, from working now?

I don't know if this is a valid consideration, but thought I'd ask.

Thanks

[ScottE]

I have sent my Sigma 105 mm macro lens back to the distributor twice to have the imbedded computer chip upgraded, once when I got my EOS 3 and again when I got the 20D. There was no charge and the lens was back in about 10 days, working with the new camera and professionally cleaned. There was no cost to me other than shipping to the Sigma distributor. They even paid for the return shipping.

On the other hand, my Sigma 400/5.6 APO work with all my Canon film and digital cameras until I got the 20D. It won't work with the 20D and Sigma cannot upgrade the chip because the lens has long been out of their product line and they aren't doing any more upgrades. I sold it to a guy who thinks his 35 mm film cameras will last forever.

In summary, Canon will make changes to their lens programs that will make some third party lenses malfunction, but the better manufactures will produce upgrades to lens that are in thier current and recent product lines, but not for long obsolete lenses.

[ttmatsu]

Tamron does not have any history of compatibility issues. Sigma has a long history of chip compatibility issues. Just speculation on my part but it could be that Sigma tries to exactly replicate what Canon did so when Canon introduces something different, the command doesn't translate. Tamron and other vendors may just provide the basic functions required.