Error 01 with lens and 6d

a 550D is a detachable lens camera and will not auto-zoom (it has a rubber ring that you turn to accomplish this with most lenses). are you sure you have an EOS 550D, or did you mean auto-focus?

Have a look here at the Canon Error codes

http://www.canon.co.uk/support/consumer_products/product_ranges/cameras/eos/error_codes/

According to the Canon website for error codes http://www.canon.co.uk/Support/Cons....aspx?faqtcmuri=tcm:14-754472&page=1&type=faq it seems like either a mechanical or electrical fault or maybe both. You could try taking both the batteries out (main and clock/memory) and leaving it a while, and also try cleaning the contacts of the camera and lens and try again. It doesn't look too good for you though, maybe it needs a trip to the service centre.

ERR 80 is an electronic control or imaging error. Generally it is a board failure and usually the camera has to go to Canon.

I am going to take a guess here and say you are getting an error message. Sometimes the contacts on the lens to camera do not make good contact. If this is your issue, use some denatured alchol and a cotton swab for CAMERAS, not for cleaning your ears and clean the gold contacts. Never touch or attempt to clean the mirror inside the camera. This should be done at a camera store. let me know.

The lens is what focusses the image on the sensor. If you remove the lens, the sensor just receives a burst of unfocussed light.

This is the kind of error which you always risk these days in buying lenses which are not from your camera manufacturer. Error 01 simply means that the camera cannot communicate with the lens. Canon's protocols are not open standards and third party manufacturers have to reverse engineer to produce something which works. As they're working in the dark, they cannot always arrive at a solution which makes all models suit all Canon bodies.

You have two possible solutions:-

Visually inspect the contacts on the lens and the camera body and if they're anything other than clean and bright then use a clean pencil eraser on them. Be very, very, careful not to let any of the rubber crumbs into the lens or the camera body.

If that fails, visit the Tamron website to see whether the lens can be returned to be updated for other bodies. if it can't then sell it and buy a later Tamron model or better still a Canon one. They may cost more, but the results are better and their resale value is much higher.

From working with third party lenses in the past what I've found is that Canon doesn't give up the "chip" technology so the older lens can not talk to the newer cameras. I suspect that Canon does this to promote their lenses over the competition. You might be able to send the lens to Sigma and have them re-chip it and have a great lens again.

Error 01: A communication problem between the lens and the body. Try cleaning the the area between the objective/Lens and the body. If that doesn't work, try another lens. If that doesn't work, try the first lense in another body, and if that works, it's most likely the body that's broken.

reset camera by removing battery completely for about 10 seconds.
otherwise, time for service.
sounds like a processor board issue.
you can use a contact cleaner sparingly, available from frys electronics or any other electronic reseller like radio shack.
good luck
mark