It is a tough process to get right but you can make a negative better than it originally was. It can also get expensive in the learning stage if you do not control the process. I have seen 20x24 negs made from 2 1/4 originals that were cool. the problem with the process is you have the whole enlargement issue of losing sharpness. SUpposedly the digital neg gets rid of this problem. Going from 4x5 to 8x10 should not be a problem at all. If you do it well there should be no loss of sharpness. Good luck. I have made a few and I thought the process was fun, and working with film in a manner that you can watch what happens the whole time is quite neat as the silver developes.