[adwb]

Please no discussion on crop factors or dof or crop factor is the wrong term ect.

A simple question with hopefully a simple answer.

If I fit a Mamiya 80 mm lens to my K5 with a readily available adapter , will what is see in the view finder look like I have my 200 mm lens or my 70 mm lens or my 50mm lens or what fitted?

I understand that just like using a lens that was for a 35mm camera I will only see the centre portion and I don't care about the dof just what size I can relate it to .

[calsan]

Set your 70-200 to 80mm. That's it!

[adwb]

Set your 70-200 to 80mm. That's it!

so the extra distance from the sensor caused by the adapter and the different lens make will not any difference?

[adpo]

focal length is focal length, unless you've got some sort of focal reducer or teleconverter built into your adapter

[PJ1]

It will behave just like an 80mm lens on your K5 or any other camera it can be attached to. It is the angle of view which is different. Smaller format means narrower angle of view.

[interested_observer]

The lens was designed to be a specific distance from the sensor (film in this case). The adapter positions the lens to meet this criteria. So, now with the lens in the position it was designed for, it will perform as expected - thus, just like an 80mm lens. Actually since with a smaller sensor, you will be really only using the center of the lens, so you will see a bit more sharpness than usual - especially in the corners and along the edges.