My story .. I (sometimes) shoot Star Trail Photos, 5hr exposures onto film. Ive been using a Mamiya Press with fair results, mostly chasing light leak issues, but it works good overall. My main issue is I dont use the set up often enough (mostly during new moon nights only, when the weather is clear, when my schedule allows) so a roll of 120 film sits in the camera for long periods of time. I want to change over to 4 x 5 sheet film so I can shoot single photos and send them off for processing individually and quickly. (I know I should just shoot more images!) The lens LF lenses are $$$ and I need to shoot at 5.6 or so f-stop where most LF lens dont go (very well at least). Ive been thinking about morphing a MF lens onto a LF camera (I had high hopes for the Wanderlust but cant hold out forever so will build my own P&S 4 x 5). MF lenses are much less expensive on the auction block plus they are fast, usually 2.8 but they lack a shutter obviously. So I need a shutter with the B Bulb function built into the lens or added on externally. Ive never held a leaf lens so not even sure how they function let alone performing surgery on one! I thought about a Copal #3 shutter which has about 53mm opening but not sure if that is large enough to mate to a MF lens (w/special machined mounting plate $$$!). I even looked at the Packard shutters as an option, mounted inside the camera behind the lens board. I havent picked out a lens other than seeing Mamiya 645s plentiful and less than $200. And yes I know I wont get full coverage onto 4 x 5 film, I dont need it, I just thought a MF lens for cost and sheet film for convenience would be a good marriage for this special purpose camera. Thanks for your feedback.