I know that lens can come in many formats, e.g. crops vs. full frame. However, someone recently told me that the Zeiss Otus has an image circle that is larger than the intended format. This is one reason why the Otus is so good and also similar things can be said about the Sigma Art lens or so I'm told.
Besides buying the gear, and a medium format back and the adapter to fit it on, is there any easy way for me to know how big of an image circle a lens has?
It seems that using a image circle for a format that's smaller than it improves the corners a lot since you're not taking the edges of the image circle?