good day... a question for the physicists among us. i did some very basic experiments and decided that a compendium lens shade would improve my photography. i then started researching various options and was quite surprised to find the linhof shade to fit my tech IV was ridiculously overpriced and wouldn't extend far enough to be all that effective. long story short, i bought a used lindhal bello-shade, carefully took it apart, and then reassembled it using $4 worth of hardware to fit into the two holes on the top of my front standard. works great, cost me less than $30.

the openings of the shade are about 4" square. my question it thus... with an opening this large, i can pull the shade out nearly a foot without any vignetting on my 300mm lens with successively lesser amounts of extension for my shorter lenses (240, 150, 110). is it more effective to have a mask at the end of the bellows and less extension or not to use a mask and simply extend the shade to just short of vignetting? the light theory i can recall, from many years ago, would lead me to believe that there would be no difference whatsoever in the effectiveness of either method; wind buffeting from the long shade withstanding. though it has been a while for me, so i thought i'd ask the forum and see what response i got.

thanks, scott