..there is only so much a hood can do to reduce flare - especially if the (key) light source is in front of the camera. Even a 'C' lens needs all the help it can get in tricky situations. A 'blocker' like this can be very useful.
Mamiya made an adjustable lenshood that can usually be found for under $30. I have one of these and spent time just this weekend determining settings for the maximum shielding for each lens. The opening is square with guides on either side of the front.
Another possibility is to insert a rectangular mask that corresponds to the 6x7 format.
You can find the Mamiya G2 bellows shade for prices well under $100. I have a couple of them, and there are adapter rings in 77mm and 58mm for use on the 67 and 645 models. They also made a G3, which is a larger bellows shade, similar to those used on view cameras.
Mamiya made an adjustable lenshood that can usually be found for under $30. I have one of these and spent time just this weekend determining settings for the maximum shielding for each lens. The opening is square with guides on either side of the front.
Another possibility is to insert a rectangular mask that corresponds to the 6x7 format.
...a bellows lens hood has it's limitations - essentially it's a fixed angle 'cone' of variable length. Ideally it's angle should match that of the lens in use -but it cannot do that. They are a compromise, being too 'tight' for a wide angle lens and not 'tight' enough for a telephoto. The 'blocker' or 'french flag' allows more specific shading and has the bouns of being considerably less bulky.