someone somewhere had explained the technical aspect of it all to me awhile back, however, I forgot it, though, if you see this image, you will notice that it is sort of partially covered, though, i forget why. its about the 6X7 and the Polaroids square opening or something like that?! Untitled by a.rodriguezpix, on Flickr
Well, In a sense, that is the full coverage, since the formats are completely day and night! One being the 6X7 sensor of the RB67 and the other being the Polaroid back and its size limits. FUJIFILM FP-100C 3.25 X 4.25 Inches.
1 inch=2.54 cm=25.4mm
3.25-2.36= .89 inch/2=.445
4.25-2.76= 1.49 inch/2=.745
If your film holder has a 6cm x 7cm film gate and it aligns perfectly with the camera then you should get an image with a border 1.13cm x 1.89cm on each side.
The film gate of the holder will limit the image size if it is smaller than the cameras image gate opening; the cameras image gate opening will limit the image size if it is smaller than the film holder film gate. Positioning of the film holder film gate with respect to the camera image gate opening will determine the border positioning.