[slackercruster]

Can T mount lenses be adapted to the 645D?

[RioRico]

No. T2 register (flange-focal distance) is 55mm while 645D register is 70.87mm. That's almost as bad as trying to fit a Leica screwmount lens to PK. No infinity focus; extreme closeup only, with vignetting. Sorry.

[slackercruster]

This is an area the 645D sucks in. Trying to fit 3rd party lenses to it.

[RioRico]

I'm not familiar with registers of MF ILC's; I just happened to find the 645D data. I read that the 67 has an even longer (but unspecified) register. So I have no idea if Kiyev, Hassy, Mamiya, Bronica etc have any chance of being adapted to the 645D. Hmmm, maybe I should add those cams to my database. What WILL work, if you can find a 645-mount bellows, would be my cheap favorites: enlarger-projector-xray-LF lenses.

[drougge]

Pentax 67 is 84.95mm. Pentax 645 actually has a pretty short register for an MF SLR, the only one I know of with a shorter distance is Mamiya 645. Pretty much anything made for 6x6 (SLR) or larger is adaptable as long as its a reasonably normal design, though not everything has adapters. (So things that need to be focused by the camera might be difficult, though they also tend to have such long registers you can probably fit a bellows.)

[itshimitis]

This is an area the 645D sucks in. Trying to fit 3rd party lenses to it.

It doesn't suck because you are comparing availability of third party lenses to the Full Frame 35mm and APS-C markets which are different because they are larger markets. You won't fine Sigma making medium format lenses as they would be unlikely to recoup much of their R+D expenditure from a much smaller group of shooters.

Also there is a specific thread a few threads away from this one that carries a database of third party adaptors. Using the search facility can often pay dividends!