Unless I misunderstand what you're saying this statement is incorrect. 1:1 has nothing to do with sensor size. What it means is that when the lens is in macro setting for 1:1 and the subject is in focus. the size of the subject on the final 100% print will be the same as the original - e.g. you take a picture of a coin at 1:1 and then print the image at 100%, the image of the coin in the picture will be exactly the same size as the actual coin, i.e. life size.