Introduction

Canon has today posted firmware updates for the EOS 350D (Digital Rebel XT), EOS-1D Mark II and EOS-1Ds Mark II. Each update addresses slightly different issues, in the case of the EOS 350D update this firmware includes a fix for 'extreme underexposure when using some lenses', an auto power off issue and an incorrect flash WB issue. The EOS-1D Mark II and EOS-1Ds Mark II updates fix a camera hang issue which could lead to a loss of buffered images (this appears to be the problem discussed in an advisory issued two weeks ago).
This firmware update incorporates the following improvements:
1. Fixes the phenomenon of extreme underexposure when using some lenses.
2. Fixes the phenomenon of auto power off function failure when auto power off is set more than 2 minutes.
3. Fixes the phenomenon of incorrect white balance when using an external flash.
This firmware update applies to cameras with firmware versions up to 1.0.1 installed. By installing this update, the phenomena will be fixed, and the affected cameras can be used without these problems. If your camera's firmware is already version 1.0.2, it is not necessary to perform this update