yeah a google search shows
this post by Roland stating that the 2.7" focuser on the traveller won't vigentte when imaging onto 35mm:
The Traveler itself is not the source of any vignetting. The inside
dimensions of the 2.7" focuser allows much bigger than 35mm coverage with no
vignetting. Adding the Field Flattener again does not cut into the light cone of
a 35mmfield. If any vignetting does occur, it will be at the very rear end at the
T-ring. It is the T-ring opening that could potentially restrict the light
reaching the 35mm film plane. Check the size of the opening of your camera. For
full unvignetted coverage, your camera opening, including T-ring, must be larger
than (34mm^2 + 24mm^2)^1/2 in diameter (does anyone know what I just wrote
there?)* Unfortunately, we have no control over camera manufacturers and their
T-ring system.
Roland Christen