Yellow frame vs actual exposed frame with Mamiya 7 / 80mm

[Karlovak]

Why does my Mamiya 7 expose a tad more on the right side, like shown in the image?
Needing horizontal calibration?

 

[Larry H-L]

I would say that your results are typical, frame lines are used as a guide only.

Most all rangefinder cameras show more on the actual image, than they show looking through the frameline guides.

 

[Karlovak]

Well.. clearly