Hi, Notice： If your camera indicated "lens is not properly installed", please modify the camera menu settings. Usually called the "release the shutter the lens is not installed", you can modify the settings to be allowed. Specifically refer to the camera manual When using the adapter ring for the first time, please say that the "No lens release shutter" option in the body menu is turned on, otherwise the lens will not be recognized and the shutter will not be used to take pictures. 

Hi,this is not compatible. 

hello， The Nikon-EOS adapter ring fit for nikon AI mount lens and canon EF camera. so the adapter ring fit for your Nikkor 55mm 3.5 ain’t lens on to canon 80d 

Hello the filter size is 58mm, so as long as your lens size i s58mm, the filter can work with your Canon EOS 20D 

It's about the zoom. It's about the diameter of the lense. If you look at the lense from the front, there should be a number. Like mine says 77mm