Can I Cut The Light With The Shutter
Setting?
Bolex D8L shutter settings varies
from about 180 degrees (the silver half-moon) to zero degrees (the black
half-moon). The half way setting of 90
degrees is accurate enough. So the answer is yes, you can a light cut 1 stop by
selecting the mid point shutter setting. Controlling the light with the shutter
does works well in still photography as the images are not moving.
If you set the shutter to
half-closed (the half black/half silver HALF MOON symbol on the shutter dial),
that setting is half way from the maximum open of 180 degrees to fully closed.
About 90 degrees. The shutter angle will
be cut by 1 stop. See page 47 of the Bolex D8L manual.
See this link for more of how
a shutter works:
D8L accuracy is not
specified, but it should be in "ballpark acceptable". As with all
footage shot on a Bolex, keeping records of the setting and the results is a very
good idea. Everybody's mileage will vary as the camera settings/projectors/screen
combinations will always be different.
Movie Film Camera
Use and effect of the shutter
is slightly different with a movie film camera. There are 3 basic ways to
set light with a motion picture camera:
1) Set the iris for the light - The
DOF will be what
it will be. This is how the Bolex manual explains
setting the iris for the light.
2) Set the pre-selected DOF with the iris,
and
control the light with ND filters or more light.
3) Use both ND filter and iris
settings in
combination.
The method of setting light
in professional motion picture film production cameras is primarily through a
pre-determined iris setting (f-stop) and then re-adjusted for actual light
using neutral density (ND) filters. Typically you will have either too much
light or not enough.
With too much light, you can close
the iris slightly or add an ND filter. Too little light, open the iris or take
out or decrease the ND filter's strength. The situation here is changing the
iris will affect the depth of field (DOF). ND filters will not affect the DOF.
How To Set
First, you select the
location (indoors or outdoors) and the subject. Say you desire an f~5.6 setting
for a slightly blurred background. Using your lightmeter, get the approximate f-stop
setting by metering the subject after dialing in the f-stop for f~5.6 on the light
meter's dial. Next, add or subtract light, as necessary using ND filter, bounce
cards, light fixture, etc, to get the correct amount of light.
More Or Less Light
Outdoor light can be raised
with a bounce card, an auxiliary hot light, etc. Outdoor light can be cut with
an ND filter and anything that will lessen the light falling on the subject. Indoor
lighting can be adjusted with bulb changes, additional lamp fixtures, scrims,
etc, or ND filters. Obviously this is more work than just turning the iris to
f-8 to chop 1 stop of light.
Effect of Short Shutter Angle
On The Look Of The Film
If you use the shutter control
to chop that one stop of light, the resultant moving picture image(s) will also
be changed. The shutter's angle is now at a shorter angle of 45 degrees and can
now impart a "stuttering appearance" onto the film depending on other
settings. See "Saving Private Ryan", or The Gladiator", for
examples of short (45 degree) shutter angles.
Also keep in mind that shorter
angles will affect panning rates. Anytime a panning rate exceeds a particular
speed/shutter angle/FPS settings, a corresponding condition will be created called
"Rolling Shutter". Also known as "The Jello Effect" because
of the look of the effect on the finished film. The rolling shutter/jello
effect has been with filmmaking since the 1st film camera was invented. Is due
to too fast of a pan rate and is 100% operator controllable. Got rolling
shutter? Pan slower.
More here:
ND filters or gels can also
be used over windows to control light. Windowed gels can be used in conjunction
with other lens filters to allow sunlight to be shot with indoor film. Or you
can gel the indoor lights to match the outdoor light color temperatures coming
through windows. With a film camera there is no white balance to correct for
off-white conditions, but you can have the film converted to digital format and
balance the digital footage if the color is slightly off.
Here's a link with some more
info:
And finally, there is a somewhat
rude, but technically correct answer, as to the effects of small shutter angles
in a motion picture camera:
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