SAm,

Are you trying to stop motion or simply attempting to use the equipment under bright conditions with film speeds that require such fast shutter speeds? If the latter, consider using neutral density filters.

I use this solution when I want to shoot at f/4ish with my Verito and similar speed portrait lenses in barrel. I have 2.0 & 3.0 ND filters that block 6 2/3 and 10 stops respectively. This allows me to use films like TMX 100 & TMY 400 at f/4 in daylight conditions with a Packard or a hat.