It's likely that the electrical contacts on the camera body and/or lens are dirty. Since you're having the problem with two lenses, you might check the camera body first. Rub the contacts gently with isopropyl alcohol on a Q-tip or clean rag. Periodic cleaning is a good idea just to make sure you don't get any nasty surprises in the field. Storing spare lenses in a clean environment with the rear lens cap on is also a good idea.

If it still doesn't work after cleaning, try the Tamron on another body (maybe your daughter's EOS) to see if you get the same error. If you do, the lens is probably at fault. If it works ok on the other body, the problem is likely in the 20D body. At least, now you've done your homework and you'll sound a lot smarter when you call Canon.

I've been using a Tamron 70-300mm lens with my 20D for many moons now with no problem. (I am now looking around for some wood to knock on.)

Bill
Thanks. I had cleaned the contacts with a pencil eraser (advice on the Canon web site) and with a clean cloth (advice from the Canon online support). Neither worked. After your email, I tried a Q-tip and isopropyl alcohol. None of these approaches worked. My Canon 18-55 lens works fine on the body. I will try the lens on a different camera and contact Tamron. I do keep the rear lens cap on the lens when it off the camera and mostly it stays on the camera.
Thanks for answering!

I had to take my camera in last week because of the Err99 message. The store manager tried every trick he could think of but still couldn't get it to work so he had to send it out. I have a trip to Cancun this weekend and hope they have it back to me by then

Hi,

I think you are wise to get in touch with Tamron about it. There is likely an incompatibility issue between an older third party lens and a newer camera body like you are trying to use. At least check their website to see if there is an info. If not, they might be able to tell you something via email.

Canon pretty much guarantees all their lenses will work with all current and future cameras (with only the EF-S lenses deliberately limited to specific models). Unfortunately there's no such guarantee with third party lens manufacturers, who sort of have to reverse engineer their lenses' electronics using the camera models that are available when the lens is being designed. They can't anticipate future changes that might occur, the way Canon can with their own lenses and cameras.

Other things you might try:

Have you ever replaced the little button "memory" battery in the camera? Those should have a life of about 5 years, but that could vary.

Have you ever updated the firmware in the camera with the latest download from the Canon website? (This might actually make matters worse. But, who knows, it could just as likely help.)

Yes, cleaning the contacts is a good idea. Also clean the battery contacts (both the main BP511 battery and the little "memory" battery).

The voltages in a camera are very small, it doesn't take much to disrupt them. Finger oils, manufacturing oils, a little oxidization, or a combination of these might be nearly or completely invisible on those contact surfaces, but enough to cause voltage drops or disruptions that keep the camera from operating fully and communicating properly within it's systems.

However, a few words of warning about how you are cleaning those contacts.

First, one of the first things I was taught when studying camera repair was to never, ever use a common "Q-tip" inside a camera. They tend to shed tiny, tough cotton fibers and those can get into camera mechanisms and cause them to jam. If that happens, with the shutter for example, you can be looking at an either expensive repair or having a paperweight instead of a camera!

Use a clean, lint free piece of cloth instead. Or, use a "clean room" type swab (Pecs Pads, etc.). Thomas Tomasy - one of the long-time, most respected repairmen and instructors - actually recommends using small pieces of paper towels or facial tissues. But, mostly he works on older, mechanical cameras that tended to have larger tolerances than today's. So, frankly, I'm not sure I'd feel entirely comfortable using those either.

Isopropyl alcohol (rubbing alcohol) is a good degreaser and might also remove very mild oxidization. There is a stronger deoxidizer called DeOxit that's even better, if needed. I think if you Google you will find it. One place I think sells it is www.micro-tools.com

On the other hand, I think those lens-to-camera contacts in Canon are gold plated, in which case oxidization can't be an issue (gold plating doesn't oxidize, which is why it's used on critical contacts). Oxidization may be more likely on the battery contacts.

For one, wipe the silver button "memory" battery to be sure it and it's contacts don't have finger oils on them (or manufacturing oils, for that matter).

I've done it myself, but stopped using the eraser trick, despite Canon's recommendation. There are several reasons. For one thing, pink pencil erasers are actually made from vegetable oil, so might not remove residual oils at all, or might even leave some behind. Also, erasers tend to shed tiny particles, too, which I really don't want getting inside my camera. Finally, white pen erasers have an abrasive in them, which can scratch and damage, possibly with a lot of use even remove protective metallic coatings, like the gold plating noted above.