Hell, My 90mm works on my 5x7 camera. So the coverage for that is good. therefore if I use it on my 6x17mm camera, which is 2.25x6.69" it is still inside the circle. Sorry Ole, Once I got out of dental School I tried not to get to involved with math since I use it everyday at work the last thing i want to do is squirrel over math instead of photographing. But impressive it is.