Hello, I have some newbie gel filter questions. I have an old Mamiya G2 Bellows Lens Hood for the RB67. It may even be an earlier version, because the back looks slightly different from the G2 pictures I could find online. It was a hand-me-down and I believe it is missing the front mask that is used with the 360mm lens. Where do you put the gelatin filters and what size gel and gel frame does it take? At first glance, I would assume they go in the front slot where the 360 mask would normally go (there is no other slot). The problem I see is that all the literature I can find says that the G2, as well as G3, take the 3" filters... but the slot at the front is 4". Do the 3x3 filters go in a 4x4 frame? Will the Kodak filter frames for the 75mm wratten filters fit in the front slot? After having some slides ruined by the sickly blue-green cast of metal halide floodlights, I'm on a serious mission to color correct without resorting to Photoshop. Thanks.