Originally posted by RuiC Because they use a special 645tok adapter the FOV stays the same!!! A 120mm 645 lens will have the very same FOV when used on a Kmount FF camera!
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Pentax 645 K-Mount Adapter?? - Photo.net Pentax Forum "
" The 300mm 645 lenses give you same FOV as the 300mm k mount versions. "
Uh... no. The FOV of a 300mm lens on any camera is the same without respect to which 300mm lens system the lens is from as long as the image circle covers the entire film or sensor.
So Take an 8x10 300mm and put it on a Sony A7 or a Pentax K3 or a Pentax Q - each system will show the same FOV it would show for a native 300mm mount. So the Sony will show the FF equivalent FOV, the K3 the APSC FOV, the Q the mega zoom fov that it does.
What doesn't happen is that you don't take a 300mm 645 lens and see the same FOV it offers on film or even digtal 645 on the K3 or the Sony or the Q. In each case the FOV seen on the camera is the same as a native 300mm lens - because focal length didn't change - just the part of the image you were able to capture.
SO when you put a 120mm 645 lens on the K3 - you see the same FOV you would normally see for a 120mm K mount but that FOV is nothing like what you see on the 645d or z or even a film 645.