The scanning area for transmission is approx. 3" wide by 12", the length of the glass . In order to do 4x5 scanning one must scan 1/2 plus of a 4x5 neg and then turn it around and scan the other half. Then photomerge them together. Jeremy figured this out and and it works! Iv'e only done one neg. so far but came out nice. Thanks Jeremy! So it is possible. Very cool!