For the canon eos d30 d60 350d 400d 10d 20d 30d 40d 50d 60d 5dmkii 1dmkiimkiin and the 1dsmkii the ex ep15 eyepiece extender extends the cameras viewfinder by 15mm thus bridging the gap between your eye and the viewfinder this allows operation of the viewfinder without the needing to press closely to the back of the camera and is more comfortable to use the viewfinder extender also reduces the image size which can be useful in assisting compositionplease note this will not