Big mattebox, little lens... solutions?
 

My Cavision mattebox that once fit perfectly snug over my 14x lens on my HD100 now hovers around a much smaller Canon FD lens. How do you guys adapt mattboxes down to these little lenses? It is rail mounted, but there's a ton of room between the outside of the lens and the inside of the box.

I carve a foam insert that covers up most of the extra room. It's not a perfect fit, but it basically blocks the light.

I use step up rings on my Cavision matte box. Since most of my Nikon lenses are 52mm, I have a 52-58 stepup ring and a 58-82mm stepup ring.

Ah! Off to the local camera shop for me. Thanks!