I have a Canon EOS40D with a Canon EF 28-135mm lens. I'm getting two spots on my images - looks like dirt but I've cleaned the lens repeatedly and it doesn't help. You can see the spots on a plain background - like a blue sky. Thanks.

I would recommend a Canon repair facility, the lens housing would need to be dis-assembled which requires precision and high degree level of skill. Canon is one of the better products and they do a professional job with warranty, check out pricing .

Make sure you're holding down the lens release button, which is located on the front of the camera, while turning the lens. Sometimes a little bit of force is needed, I've found new lens' can stick a little bit. If it still won't come off, contact Canon.

Taking the lens off and back on does nothing unless you clean the gold contacts on both the lens and camera body. Most common method is to use a clean pencil eraser and lightly polish the contacts. Do this while the lens is inverted to help prevent dirt from getting into the lens cavaity.

Also the camera body try to hold the lens cavity downward to help prevent dirt or dust from getting into the camera Gently polish the contacts. You might want to do this with all your lenses and battery contacts.

The Error 99 is Canon's way of saying electrical communications are at fault but they don't tell you which one.

Also doing a camera firmware update often times works the best for this error code.

Sounds as if there is a fleck of dirt on the rear lens element. While in the house (to minimize dust and dirt) remove the lens and look at the rear of the lens see if there is dirt there. If so clean it gently with a soft lens cloth not a facial tissue. Reinstall the lens, if the dirt is still in the same spot return the camera because I suspect the dirt is on the sensor and will need to be cleaned.

Most likely it is dirt/dust on inside the lens. If it is in the bottom of the picture, the dirt will be on the top edge of the lens. If it is inside the lens, you will probably not be able to clean it your selves.

I had this problem too, then my camera started getting Error 99 (there is some problem) and not working.
If you look at this website and follow the steps under Update 2
http://www.richardsnotes.org/archives/2005/04/29/50mm-lens-contact-points/
I think you will fix your problem. The connections between lens and camera probably have a little dust in them, use a soft rubber eraser to clean them. Make sure no dust or pieces fall into the camera or lens when cleaning!

Check for clean lens to body gold contacts.
Take the lens off the camera. Look at the gold contacts that are in the body and on the lens. Many times, it's a simple process of rubbing a pencil eraser on these to remove dirt/film on them to allow proper contact. BE CAREFUL not to allow eraser crumbs to fall in the camera body. You can tip the opening slightly downward while you're cleaning... a lens brush can help remove any crumbs too
Let me know if it clears up your error.
K

Hello. First, check the contacts on the lens mount--you're looking for bent pins, oxidized(odd-colored) metal, damaged contact points, etc. The camera must communicate reliably with the internal circuitry of the lens unit. If there is any dirt, moisture, intermittent contact going on, the sensitive focusing electronics will be effectively blinded. If all is fine with the contacts, then the problem lies with the circuits in the lens that provide critical focusing data to the camera. Movement of certain parts causes electrical changes to occur at a calibrated rate--if the camera loses connection, it can't tell if the lens is actually adjusting. You'll have to send the lens in for repair--http://www.usa.canon.com/consumer/controller?act=SupportIndexAct. This address should get you started.--Hope I helped!---Rick

there is a manual for the 40d kit with that lens. probably does not have exactly what your looking for but there is some useful info about that lens here is the link .

http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=SupportDetailTabAct&fcategoryid=215&modelid=17779#DownloadDetailAct

Check with your local Camera store first or the makers website before you get handy. A very soft and fine make up brush may come in handy But check it our first