On a recent shoot with the Canon 5D Mark II I lamented the lack of properly-sized donuts. Now, thanks to Abel Cine, I lament no more.
Just today Abel Cine posted on its web site a kit that allows use of an Arri MMB-1 mattebox system with odd-sized still format lenses.
The primary purpose of a mattebox is to hold filters, but filters not only pass light–being shiny glass, they reflect it. Any light that seeps in from the lens side of the mattebox will create reflections that have to be eliminated or they’ll completely ruin the shot.
In this picture the “donut” is the round gasket-looking thing at the rear of the matte box that consists of a rubbery bellows with a hard plastic ring inset. That ring is removable and comes in different sizes that fit perfectly around whatever lens they are made for. A tight seal between the lens and the ring/bellows system prevents any light from sneaking in the back of the mattebox and ruining a shot.
A mattebox system like this would have shaved a half hour and 30′ of 2″ black paper tape off of my last Canon 5D shoot.