Rain Deflector Matte Box
This system is suitable for rigs because most of it is not on the camera. The
rotary window rain deflector units are very good and will work in most situations.
This unit will not stop water splashed from a puddle by a tire, but works well
with rain and snow, even while driving and shooting straight ahead.
This system would not work well for a large zoom lens, as it would take a very
large volume of air and matte box.
The key is a high volume of air from a 12 volt DC blower that blows a lot of
air forward out of the matte box blowing the rain forward and to the side. We
tried high-pressure air directly into the matte box with no success. The high
pressure created eddy currents that actually pulled rain into the lens. C and
H Sales in Pasadena Calif. usually has a good selection of blowers.(818-796-2628)
A "squirrel cage" or "axial" blower of least 200 CFM (Cubic Feet per Minute)
is needed. A 24-volt fan may work well enough on 12 volts. A good unit should
draw 2 amps or more.
If high-pressure air is allowed to expand BEFORE it gets to the matte box it
would be OK, but it takes a lot of air. You need to keep the lens clean the
whole time the camera is facing the rain and not just while the camera is rolling.
CO-2 could cause condensation.
Avoid using much corrugated flex hose because it will reduce the airflow. For
low angle rigs we often use the support or bracing pipe as the air pipe to the
matte box. 2 inch IPS aluminum pipe is good.
A modified Arri II C matte box will work with the air coming in the top though
a large hole. Tape off any air leakage around the sides of the box.
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