EOS 550D Firmware Update Version 1.0.8
Firmware Version 1.0.8 incorporates the following fixes.
Changes in this version:
Fixes a phenomenon in which the set aperture moves unexpectedly when shooting movies in manual exposure mode using some lenses (such as macro lenses).
The Version 1.0.8 firmware is for cameras with firmware up to Version 1.0.7. If the camera's firmware is already Version 1.0.8, it is not necessary to update the firmware.
Supplemental Information:
This phenomenon involves the aperture of the lens moving unexpectedly when the focusing ring moves (during focusing). Please note that aperture values also change when operating the zoom ring of a zoom lens that has variable maximum aperture values; however, this is a normal operation because the camera controls aperture values properly depending on the focal length (zoom position).
Further information: