Making a Solar filter with Baader Film

Hey everyone,
I've ordered a sheet (7.9" x 11") of Baader Solar film and want to construct a filter for my C11. So, I'm wondering if I should make a 7" dia. concentric filter, or a 4" - 4.5" off-axis filter. The concentric construction has the relatively large central obstruction, whereas the 4" off-axis has a clear light path. Which one would give the sharpest, highest contrast image? Thanks for any insight here!

Steve

The Baader film is inexpensive enough you might as well make a full aperture filter and take advantage of the additional resolution. Then , if you really want to try an off-axis filter you can simply put a cardboard mask in front of your filter, best of both worlds.