This may sound strange but I have to ask this question. Recently I got Pentax 645N camera without lens. Will Pentax lens for 645 camera fit models 645, 645N as well as model 645NII? Thanks for any help you may provide.
Yes. The 645 lenses fit and work on the 645N. Of course they will not AF but the focus confirmation dot works and MF is not a problem with the big and bright viewfinder.
The only (slight) incompatibility is that on the 645N the aperture recording on the film (if enabled) may be off by half a stop.
The 645NII afaik uses the same lens lineup as the 645N.
all lenses are compatible across the entire range.
you'll of course lose AF capability with the FA lenses if using them on the P645 (1st version, non-N/NII)
Slobo, if you are not shy of a bit of extra weight, also consider Pentax 6x7 and 67 lenses via the P67-to-P645 adapter. They work similar to the P645 manual lenses, including AF confirmation and automatic aperture closing.
Slightly OT but I had an non-af early 75/2.8 lens and it was phenomenal in my opinion. The adapter idea is excellent as well, many 67 lenses are selling for a song.