When I mentioned lens shutters I was thinking of the Mamiya RB/RZ series as well as Hasselblad, Bronica, etc. All have leaf shutters with the Mamiya only going to 1/400 second. I was just curious how the PhaseOne backs were able to perform on these cameras at all. I realize the 645D has a top of 1/4000 and is also 3X the price of the D800. For me to go high pixel count it will most definitely involve a FX sensor vs MF sensor due to price, unless I find a screaming deal on a used sensor.
Really not trying to buck the system, I just like to use small apertures for maximum DOF, which necessitates a slower shutter speed. I'm just trying to determine if I would be better off with the D800 or possibly a used D3X for my particular needs. I only mentioned the Pentax 645D because I thought I saw a used one for about $4K USD. If I did it must have fallen off a truck.
I'm definitely not opposed to tripod use. Don't mind locking up my mirror if I need to. Again, just trying to understand the sensor resolution issue so that I can make the right choice for me and my style of shooting.
I recently purchased a Bronica ETRS as well as a GS-1 system. While I do love shooting MF with film, I have come to realize that after factoring in the costs of "quality" processing to include film development and scanning, I'll have to take out a second mortage on the house to afford this route. My primary lens on my D2X has been a Tokina 20-35 since I got it about 3 months ago. Absolutely love it. I do have 300mm & 400mm primes but as yet have not had a chance to use them.
Thank you again for taking the time to respond and help to clarify some of my concerns. It appears I have a considerable amount of research left prior to my next camera purchase.