Just getting my journey started here....went with a easy entry point cost wise and jumped for a used 645D and 75 mm f/2.8...any advise or tips for a newbie into the MF world is greatly appreciated...
Welcome. Nothing to fancy with MFD, they are just cameras and the 645D is one of the most advanced. I really like the D FA 55mm and I have the A 35mm and A 120mm macro, both really nice lenses. I do have a 300mm, but don't use it very much. FA are autofocus, A are manual. Some the the Pentax 67 lenses work well on the 645D as well. There are lots of places you can find lens recommendations. The Fun with the 645D thread is in the Pentax forum of GetDPI, but I usually post my 645D images here.
ISO 1600 is really good on the 645D and I have a lot of fun using it for street photography when I get to urban locations. This is not just for landscape pictures. The mirror is well dampened and with a bit of practice can use slower shutter speeds, but don't be fooled by the 100% monitor view--on a 24" monitor in Photoshop, you are looking at about a 9mm x 5mm section of the 44x33 chip. Just like viewing a 44"x33" print from 10". I regularly print images from a 44" wide printer and the results are wonderful.
BTW, if you have Leica Visoflex lenses, you can get an adapter to mount them on the 645D. Maybe not the best lenses for the 645D, but it could be fun.