For all Canon EOS series DSLR except the 7D & 1 series, the EP-EX15II Eyepiece Extender extends the camera's viewfinder by 15mm, thus bridging the gap between your eye & the viewfinder. This allows operation of the viewfinder without the needing to press closely to the back of the camera & is more comfortable to use. The viewfinder extender also reduces the image size, which can be useful in assisting composition.