SCOPE
This FAQ covers all 8 mm
spring motors from 1940's thru 1960'S.
GENERAL
The vast majority of all 8 mm
film cameras sold from 1940 up through the 1960's have a flat spring wound
motor to drive the film train. A spring made from tempered steel is wound into
the shape of a coil. The spring coil is mounted on a shaft. One end of the
shaft winds the motor's spring with a folding key.
When the camera's run button
is depressed, a one way clutch holds the winding key in the same relative
position while the now compressed (wound) spring tries to unwind itself. This
unwinding causes the case of the spring motor to turn. The turning motion of
the case outer ring gear powers the speed regulator which controls the rate at
which the spring motor unwinds. Typical setting are: 8, 12, 16, 24 36 48 and 64
Frames Per Second.
Bolex 8mm cameras (all except
the H8 series and Super 8) are infinitely variable with a dial to indicate the
approximate frame rate per second (FPS). Other cameras such as Bell &
Howell and Revere (and others), use a selector with a specific FPS
setting.
Following the winding
procedure found in your camera's manual. The number of winding turns varies
depending upon the make of the camera. Bolex cameras are fully wound at 21 1/2
turns or at about 11 full turns. There is a slight variance from motor to
motor. Other camera such as Revere's, Keystone, and Bell &Howell's
typically are fully wound at approximately 8-10 full turns.
Cameras other than Bolex wind
until the spring is fully coiled. The maximum winding is mechanically limited
in Bolex cameras. This allows the motor to be wound to a hard stop. Bolex's are
advertised as "impossible to overwind" and uses a mechanism to
prevent the camera from being overwound. For the most part, it works as
advertised. However it is possible to overwind a Bolex. It takes a lot of
forcing, but it can be done.
RUN TIME PER FULL WIND
The run time per full winding
is shown below:
MODEL: RUN
TIME
Bolex (All 8mm models except for H8) 20 seconds
Revere 44 10 seconds
Revere K-45 25 seconds
Revere 99 15 seconds
Keystone K-38 25 seconds
Keystone K-36 35 seconds
NOTE:
The
above are average/typical run times measured from full
wound to
full stop.Not all of the running time is usable,
however.
Except for the Bolex, all 8mm cameras typically will run from fully
wound to stop at a
speed approximately that which is dialed in.
I.e., 24 FPS will film 24 frame per
second. However, at some
time after the initial start, the motor's speed WILL slow down
time after the initial start, the motor's speed WILL slow down
and the FPS will become lower.
WHY?
The location (time) of the
slow down will vary from camera to camera within the same model designation. It
depends on the age and condition of the motor and at what wind point the camera
was stored. Spring motors left fully wound can loose their elasticity
(springiness) and will not last an average full wind. Spring motor cameras
should be fully wound down when not in use.
SLOW DOWN
Slow down means that after
developing, the finished footage will play normally (at the selected filmed frame
rate) and the will "speed up" at some point in the clip. This
"speed up" is due to the filming frame rate of the camera slowing
down and the projection rate of the projector staying constant.
OTHER PROBLEMS
Cameras that have been left
fully would can sometimes develop a permanent "kink". This
"kink" is a weakness in the spring and can be felt while filming with
the camera. It feels like a bump, thud or clunk. Sometimes it can be heard -
sometimes only felt. The kink, depending upon the severity of the damage, may
not be noticeable. The fix for this is usually to replace the motor.
REPLACEMENT MOTORS
There are no new motors
available for any 8mm cameras. Nobody rebuilds them. Therefore a donor camera
for parts is required. If you purchase a donor camera, be sure get the same
model or a corresponding model with the same motor dimensions. Bolex cameras
all used the same motor except for the H8 series and possibly the L8 model.
Ask the seller if the motor
is usable. Given that these cameras are all over 50 years old, finding a donor
camera may result in your having to purchase multiple cameras to get a good
motor. Be advised that typical sellers do not know whether or not the motor is
usable. The may state, "It winds and runs". They may not notice that
the motor is unusable.
If you buy a camera with a bad motor and the seller has NOT agreed to take it back upon your inspection, you can always resell the camera.
If you buy a camera with a bad motor and the seller has NOT agreed to take it back upon your inspection, you can always resell the camera.
USABLE RUN TIME
All camera manuals have
information giving the usable run time for a full wind. This information is for
a new camera. All 8mm cameras are now 50 plus years old. You will need to allow
for this. All spring motors will have lost some of their usability after 50
years. You can wind and run the camera to the point at which you can clearly
notice the motor running down.
EXAMPLE
If you fully wind your
Keystone K-38 camera and it begins to run down at 17 seconds, you should stop
filming and fully rewind the camera after 10-15 seconds. During filming, you
can count (in your head) 1,000-one, 1,000-two, 1,000-three, etc. It was and still is good
operating practice to fully wind the motor after each shot. Shoot for 3 seconds?
Rewind - now. Shoot for 10 seconds? Rewind - now.
BOLEX IS THE EXCEPTION
Bolex cameras are the
exception. A Bolex 8mm camera, in good operating order, can film for about 20
seconds. When the Bolex motor reaches the end of the wind it will stop abruptly while turning, and filming at the same FPS.
If a Bolex motor begins to
slow down while filming, it is because the motor is weak. Depending on how weak
the motor is, it may or may not be serviceable. Because of the limited run time, 8mm film cameras don't do well for interviews or documentaries.
FILMING TECHNIQUE
Good filming technique with
any 8mm camera demands that the operator plan each shot prior to shooting. The
means the you will need to keep track of the clip (shot) length (counting
seconds in your head) and camera distance, focus and location. Failure to plan ahead
will mean you will need to shoot more footage and your filmstock and developing costs will go up.
AVOID JUMP CUTS
Starting and stopping a
camera can result in a "jump cut". Imagine on overhead view of the
subject and the background. If the subject turns to either side slightly, and
the camera is stopped and then filming starts in a slightly different location
or angle, the subject can appear to "jump" from one place to another.
Keystone Cops style. Moving the camera at least 15 degrees off axis between any
two consecutive shots at the same distance to avoid a jump cut. Read more on
Jump Cuts here:
Try moving closer or farther
away from subject to prevent a "jump cut". After shooting, you
can edit in/out similar angles or distances after filming to better tell the
story. Advance planning always helps.
Not planning will waste film and result in a poorly made film.
TELL A STORY
1) Parents leaving on a plane for
vacation,
2) Kids
graduating,
3) Cat playing with dog,
etc.
Think of where you'll need to
be to get the shots. Make the shots short. 3 to 8 seconds or so. Do not run the
camera until wound down for a long shot. It will be boring and you have to edit
out the bad parts, anyway. Given the cost of film and processing, this is an
absolute necessity. Good footage is built up, shot by shot.
MORE INFORMATION ON
FILMMAKING
Plenty of old
"how-to-shoot film" books on the internet. Any books on filmmaking
will help. If you are videographer, you will need to learn to limit your shots
lengths. Books:
Remember that film shot is
gone forever. No mistakes allowed. No do - over's, etc. Plan ahead.
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