HANDHELD LIGHT METERS VS. INTERNAL LIGHT METERS and SUPER 8mm MOVIE CAMERAS

Using a hand-held light meter is an excellent way to improve your movie making. Also, developing your technique in the use of the camera's internal light meter will equally improve your footage. No matter which method you choose, just be sure you make some tests before shooting your once-in-a-lifetime footage! I'll explain.

The majority of Super 8mm cameras come with internal light meters. Personally, I have found them to be very good at determining the overall correct exposure. However, you must use caution when relying solely upon the internal meter, especially in the "auto" mode. Realize that the auto mode will meter for the entire scene. Backlighting of the main subject will greatly alter your exposure levels. Luckily, many Super 8mm cameras offer some sort of compensation button/dial which will overcome this type of situation adequately. But we are looking for more professional results. Here's what I suggest:

Use the internal meter as a spot meter. Bring the camera up close to your subject and note the meter reading. Then, preset the meter in the manual position to this aperture reading. This assumes you have a camera that has both manual and auto meter settings. If you have auto only, simply try not to vary your shooting position too much within a scene - this will help minimize changes in exposure that you cannot control. Change positions then start filming again. This is the only choice you have, unfortunately.

As above but in all shooting conditions, read the aperture reading, then preset manually. As stated, this will give your films a more professional look. For instance, filming from a car while going into, traveling through, and exiting a tunnel. If the scene is a continuous one, you would definitely want to preset the exposure. Otherwise you will introduce a "cinematic effect" into your film - the audience will notice the automatic opening of the aperture once the camera is in the darkened tunnel. This is a "no-no" unless this is what you truly want. A better method is to shoot the scene entering the tunnel with the aperture fixed. Stop filming once in the tunnel and then expose for dark conditions, continue filming. Then, stop filming prior to leaving the tunnel and reset the aperture to the setting you entered the tunnel with and continue filming. Much better! Of coarse, the favourite method is to simply let the tunnel portion of the scene remain dark and shoot the whole thing in one scene. It all depends upon what you require.

HAND-HELD METERS Hand-held meters are great for still cameras - set the ASA, set the shutter speed, push the button, and VOILA - a number appears and you have your f stop! But, movie cameras don't have a shutter speed listed on the body, only a frames per second (fps) option, if you are lucky! So, using a hand-held meter requires you know some specifics about your camera. If you don't know the shutter speed (sometimes the manual tells you this bit of information), all is not lost.

A SHORTCUT FOR DETERMING YOUR CAMERA'S SHUTTER SPEED

You can do it the easy way: come up with a cross reference sheet by comparing the internal light meter readings of the movie camera with what your hand-held meter shows. Here's how:

Set the ASA correctly on the hand-held meter. Be sure to know whether you are using the Tungsten setting of 40 ASA (indoors) or the Daylight setting of 25 ASA (outdoors), in the case of Kodachrome 40.

Then, point the movie camera (loaded with a K40 film cartridge) and the hand-held meter at the same object/subject. Note the meter reading on the movie camera, then press the button on the hand-held meter.

Rotate the APERTURE setting on the hand-held meter to match to that of the movie camera's f stop reading and the number on the display of your meter.

Then, read off the resulting shutter speed. You now know the shutter speed of your movie camera, as determined by the factory!

Please note, the shutter speed of your camera CHANGES depending on your frames per second setting!

So, repeat the above procedure with the camera set to each of the different speed settings and make a note of the other shutter speeds. Sometimes you will have to actually run the camera, so be sure you do it with an old film cartridge installed so that the ASA setting is properly set. The shutter speed is also different for single frames so perform the same procedure when the camera is set to "1."
 

A MORE DETAILED EXPLANATION

"But, wait, I still don't understand why movie cameras have a shutter speed. I thought they only have a frames per second rating," you say.

Or, you may have thought,

"This is Super 8mm, and I have no idea what the shutter speed of the camera is. Isn't the shutter speed 18 or 24 fps?"

No, not at all. The fps directly affects the shutter speed but we need to know just what that shutter speed is. The shutter speed is also affected by the cut of shutter itself. Whether the camera has a 150 degree shutter or 220 degree, or something in between.

"Boy," you say, "this is sure getting technical!"

Yes, but hang in there, it gets easier.

First, the shutter on a movie camera is simply a round plastic or metal disk with a notch cut out of it (looks like a pie with a big piece already eaten). The size of the notch, measured in the degrees of a circle, determines how "big" (or "slow") the shutter is.

For example, a 220 degree shutter means that only 140 degrees of the plastic disk actually remains. The 220 degrees is the part of the circle of plastic cut out to let light pass through to the film frame as it spins. The spinning speeds up when the fps increases, too. With a 220 degree shutter, the images recorded will be softer as more light is allowed onto the film and, since the subject tends to be in motion, more time is allowed to pass until the disk closes again. So, big shutters allow more light but make softer images.

"So, what about smaller (faster?) shutters," you ask?

Well, smaller (or "faster") shutters, like 150 degrees for example, allow less light onto the film frame, since there is more of the disk remaining. But the images will be sharper because of the less time allowed to pass to record the image on the single frame. Note, the term "sharper" is measured against a 220 degree shutter operating at the same fps.

As in everything in life, it is a give and take situation. Faster (or "smaller") shutters (around 140 - 180 degrees) mean sharper images but, as less light is passed onto the film frame, you need brighter conditions. Also, if a fast moving image is recorded with too fast of a shutter, the image will tend to "strobe" since some of the action will not be recorded on the film. This is why car and bicycle wheel spokes spin slowly and sometimes backwards compared to the actual motion of the object.

Slower shutters (around 180 - 230 degrees) mean softer images, but more light passed onto the film, hence better for very low light situations. However, since so much of the image's motion is recorded onto a single frame, the overall appearance will be softer.
 

SUMMARY

Degrees/Effects
140 Sharper images, require more light, possible strobing of the image.
150
160
170
180 Somewhere in between???
190
200
210
220
230 Softer images, less light required on subject, overall softness to film images.

Now, before we completely lose track of our mission on how to use a hand-held meter for a movie camera, let's figure this out.

Simply, a movie camera with a 220 degree shutter operating at 18fps yields an effective shutter speed of 1/29.5th (~ 1/30th) of a second.

From this, the formula is as follows:

((frames per second) * (shutter speed as measured in a fraction of a second))*360 = Shutter size in degrees

or

1/((Shutter size, in decimals)/fps) = whole number shutter speed, expressed as a fraction of a second.

1/((220/360)/(18))=29.5(th of a second)~1/30th

1/((220/360)/(24))=39.3(th of a second)~1/40th

A camera claims to have a 180 degree shutter and frame rates of 18, 24, and 54. What are the shutter speeds?
1/((180/360)/18)=~1/36th of a second (use either 1/30th or 1/40th)

1/((180/360)/24)=~1/48th of a second (use 1/50th)

1/((180/360)/54)=~1/108th of a second (use 1/100th)

Finally, you pick up a camera manual for a Bolex H8 that says to set the hand-held light meter to 1/40th of a second for 16fps. What is the size of the shutter? Note, this is not a variable shutter model!!
1/(40/16)*360= 144 degrees

So, armed with only two of three factors (the frame rate, the shutter speed, or the size of the shutter), you can now determine the missing piece.
 

FINAL DISCUSSION

Sharpness of an image is an easily measured property but, at the same time, tends to be surprisingly subjective. And so it goes with people comparing movie cameras! Unfortunately, people often compare "apples and oranges" when it comes to movie cameras, especially in the Super 8mm format.

Yes, Canon, Nizo, and Leitz lenses are excellent. But so much also depends on the size of the shutter. Quite simply, you cannot compare cameras on sharpness when their shutters are different. A 220 degree shutter cannot compare to a 140 degree "shuttered" camera. Depending on the frame rate (fps), lighting conditions, and the actual motion of the object being filmed, two high-end cameras at either extreme will yield different results! Maybe that is one reason why there were so many different types of cameras produced in Super 8mm's heyday during the 1970's.

So, you end up having a different camera for different shooting conditions. Take your Bolex 160 Macrozoom (or the Kodak M2/M4 with 140 degree shutters) when you go skiing. The relatively slow f1.8 (or f2.7) lens combined with the faster shutter speeds will help your K40 handle the bright lighting conditions typical of snow and high altitude. The 150 (or 140 with the Kodak's) degree shutter will help keep your action crisp and lively.

At the other extreme, haul out your low-light Chinon camera (the one with the 230 degree shutter and f1.1 lens) and get ready to shoot at 9fps a scene of stagnant action - say a marsh at sunset with little activity. Or, shoot at 18 fps and capture that concert scene held in the park on a Friday evening. The speed of the guitar player's hands will blur nicely into a soothing low light visual feast!