This post explains how to compensate for Kodak Ektachrome 100D and the Bolex P1 Metering system.
Kodak's suggested neutral density filters are
general suggestions for this type of film used in a "daylight"
situation to help avoid overexposure.
From the Kodak page they suggest using a .3 (1 stop)
or a .6 (2 stops) ND filter to avoid overexposure. You could also drop a stop
by rotating the iris. For example if the iris is set to f/5.6, and the needle
centered, you could move it to f/8. That will give you a 1 stop decrease in
light. The needle will show underexposed - ignore it.
If you instead used a .3 (1 stop) filter in the lens
holder of the P1, the metering system will just see 1 stop less light and you
would still center the needle. This would put the camera exposure back to what
it thinks is 'normal'. And it would be still be one stop overexposed for the
Ektachrome 100D film you are using. Keep in mind, this compensation as
recommended by Kodak is ONLY for Ektachrome 100D film. Other films may or may
not need compensation.
Keep written records of what works best. ASA, film
speeds, compensation, subject lighting, overall lighting conditions, etc, before and after shooting.
BACK LIGHT
Another situation is a "back light" scene where a strong light behind the
subject affects the overall meter's setting. It 'reads' all light in the scene
which 'skews' the overall metering values towards underexposing the backlit
subject. Although the needle in center, the meter is 'lying to you' about the
correct setting.
To fix a back lit scene, you would adjust the needle
for that excessive light and the resultant developed film would be exposed
correctly. Back light in any 8mm cameras typically calls for decreasing the
iris to a larger number (smaller iris opening) by about 1/2 to 2 stops
depending on the strength of the back light.
Three ways to correct:
1) Add more light on the subject(s) then recompose the
shot
2) Close the iris 1-2 stops (guess)
3) Get close to subject, fill the screen with the
subject, and then set the (meter). Back up and
shoot the footage.
Do NOT readjust metering once set.
See here:
For more information, search Google for these terms:
backlight
compensation
Example:
If the needle centered at F/5.6, for a typical
backlight situation, one would move the P1 camera iris lever half way (or more - depending on
conditions) from f/5.6 to f/8. The needle would read underexposed by one stop, however,
the subject would be exposed more correctly. The background light would be a
stop less, too. Remember, you always (usually) want to set the exposure for the
subject. Backlit situations set the iris for what is behind the subject. What
is really needed is spot metering.
Unfortunately spot meting is not used on the Bolex
camera. Bolex diverts all the light from the picture as seen by the lens. Under
most condition this gives a good average of the light in the scene that the
camera is shooting. But unfortunately does not allow for backlight conditions.
One way around this is to meter the subject with a separate light meter such as
a Sekonic L-398.
Here's a link to its manual:
Unfortunately, these also while doing a great job (and
at a low cost) for how they are intended to be used, the L398 cannot do spot
metering :(
You can use a spot meter to meter off the face value from
a distance or just guess the iris compensation based on experience.
Sekonic L398 Meters on eBay:
Regardless of what meter you use, using a meter can
get better footage than guessing. I like the L398 as it has FPS (cine), ISO ,
aperture, and EV settings. Just dial in numbers and take a reading. Easy
to use, no batteries, inexpensive (used).
