Purchasing a matte box with some questions
 

I think i'm going to pick up one of the spffy new o'connor o-box matte boxes and am trying to figure out what i need to use this on eng and slr lenses. It looks like the box has a 150 mm opening and i'm not sure if i need to get a bellows ring or step down rings or what? This was a little more confusing than I thought it would be, thanks for any help!

Re: Purchasing a matte box with some questions
 

If you want to use a 138 round pola (or other filter), and have 15mm rods, you buy the 150-to-114 bellows and then a step down ring to either 110, 95, or 80mm depending what lens you have. Those sizes, by the way, are common front diameters for cine lenses.

If you want to CLAMP on to the front of your lens, and don't have or don't want rods, OR you don't need 138 round filters in the bellows, you can get step down rings that allow the MB to clamp onto those above sizes.

So two "lines" of lens interfacing, if you will. One set of rings for bellows (plus the bellows), one set for clamping.

Re: Purchasing a matte box with some questions
 

Nate, this may be a silly question but what if my lens, at least the screw in element is 77 or 82 mm? I don't see any rings that fit.

Re: Purchasing a matte box with some questions
 

There are reduction rings to 80mm and 95mm. The 80mm should cover the 77mm screw, however, you may have to improvise or make a ring to the 95mm for your 82mm screw lens - I assume it's about 85mm on the outside. Some camera assistants have an elastic black cloth doughnut that they use for this.