Hi, I am trying to find out if the C-3black} Calument 8X10 Bi-camera can be fitt ed with any make of reducing backs . I will need a 5X7 back for it. I called Cal ument and they said I had to buy the frame and the spring assembly for the 8X10 to 5X7 back. $499.00+359! {new}see what I mean? That will cost more than the cam era. So if any of you know of other different makes {used} that would fit please let me here from you. Thank you, Dan