From a LF newcomer, Should I go LF (4x5)?

First of all I love this site, and your technical forums—allot of detailed info from some seemingly quite experienced folks. I currently shoot weddings (mostly) with a Nikon D100 digital SLR. I am particularly unhappy with the sharpness of prints 11 x 14 and larger. I would like to offer my clients very, very sharp enlargements (of their formals/ group shots at the alter) to print sizes up to 20 x 30. I can also see myself doing landscapes when I get time (If I ever get time). Digital scanning, image manipulation, and printing processes would be employed. I believe a LF 4x5 will meet or exceed my expectations. I believe a 16x20 print produced from a scanned LF 4x5 negative will be distincly sharper than that produced from a MF system. (Opions Please!)

However, I have reservations about speed/ease of use and adequate depth of field not so much for the large groups but for close-ups. And the over-all practicality of such an endeavor. Am I going to have to shoot at f/32 and blind everyone w/ maxed-out moonlights?

Assuming your answer to that drawn-out question is ,” yes go for it!”, I am at this time overwhelmed by the selection process—why the $160 – over $3000 price range? I’ve heard there’s really not much can go wrong with these cameras and all of them are capable of great pictures. Will I have trouble getting sharp images from a cheap camera?

At the present time I’m considering a CALUMET 45NXII 4X5—inexpensive, but quite nice in appearance to me, and going with a high quality used lens.

All suggestions are welcome