It's worth mentioning that I have found that I do have 35mm and 4x5 negative carriers for the D2, which is actually a D II. I guess there is a difference between a D2 and DII.

What's the upper bellows adjustment for on the 23C? I know the bottom bellows focuses, but does the top just adjust brightness? I found out that you can take the lens board out without using a screwdriver.