Some images captured by the EF 70-300mm f/4-5.6 IS USM lens appear in insufficient resolution. To All EF 70-300 f/4-5.6 IS USM Lens users
To All EF 70-300 f/4-5.6 IS USM Lens users
Thank you for using Canon products.
We recently informed you of a phenomenon in which some images captured by theEF 70-300 f/4-5.6 IS USM lens appear in insufficient resolution. This phenomenon may be seen at the edge of the frame at the 300mm setting when the camera is held vertically.
We are very sorry for the inconvenience that this phenomenon represents for customers who use this lens and appreciate your understanding and cooperation.
Affected Products: 
The phenomenon described above may occur inEF70-300mm f/4-5.6 IS USM whose third and fourth digits of the serial number are as set forth below.
Identification Procedure:
Serial Number: [nnXNnnnn]
"X"="0" or "1" (except "N"="7")
If the fourth digit is “7”, it is NOT affected.
"n" represents any digit.
Examples of affected serial numbers are: "nn01nnnn" or"nn11nnnn"
Customer Support
Starting from 18 July 2006, we make inspections and repairs free of charge for customers who are experiencing this phenomenon, so please contact Canon service center.
Contact Information for Inquiries
For questions about this matter, please contact our Customer Service Hotline.
Hotline Enquiry Hours
Customer Care Center Address and Opening Hours