Super 8 Film/ 18fps Shutter Speed Settings for Light Meter

[Gerald Martindill]

Hey everyone,

I'm having a confusing moment and would love some help.

Working with a Beaulieu 4008 ZMII Super 8 film camera. 

I'm shooting tonight. Using a Sekonic light meter, for high contrast scenes. ... want to make sure I have the settings correct. Had alot of anxiety the other night I **(obscenity removed)**ed up after the shoot...and have two more actors coming by tonight.. The on camera-light meter kept saying I was underexposed, but I'm hoping it's just because heavy shadows.

I'm shooting on 500Tungsten film stock. Shooting at 18fps. The camera's highest ASA is 400, so I'm setting it to that. This is a Angenieux 6-80mm f1.4 zoom lens.

I'm a bit confused on what shutter speed to put into the light meter. Should I put 1/65 a second or 1/130 of a second? I'm reading about if the shutter is "half open" divide the exposure times by two, but what exactly does that mean?

Anything helps. Thanks so much!

[Johanan Pandone]

At 18fps the shutter speed is 1/65, at 24fps the shutter speed is 1/86, and at 36fps it is 1/130

[Mark Dunn]

deleted due to ignorance

Edited January 31, 2023 by Mark Dunn

[Joerg Polzfusz]

Hi!

The exposure times are listed in the manual. (The attached table is from the manual. When you don’t have a manual then please PM me. I can send you a PDF.)

As for the shutter: In an ideal world, the film could be exposed for the full duration without any lightloss caused by the film-transport. So at 18fps, it would be simply exposed for 1/18th of a second. But in reality, the film has to be transported to the next frame after having being exposed. (Expose -> Transport -> Expose -> Transport -> etc.) That’s where the shutter comes into play: it prevents the film from being exposed while being transported. In most cameras, this shutter is just a rotating disc in front of the film. If the shutter would have no opening, then the film could not be exposed at all. If the opening would be 180°, then the film would only be exposed for 50% of 1/18th of a second = 1/36th of a second.(remember your maths lessons at school: 360° = full circle, 180° = half of the circle, 90° = quarter of the circle etc.) On most cameras, the opening is something between 145° and 180° wide. When you have got an XL-camera, then the opening is usually something between 200° and 230°. (Note: Your Beaulieu isn’t an XL-camera. But it has got a „variable shutter“. So you can reduce the opening, e.g. for doing fade-outs as in in-camera effect. When you don’t want to do a fade-out but reduce the shutter opening anyway (artistic reasons, special lighting conditions, …), then you would have to calculate the effects on the exposure duration.)

Theoretically, you could calculate the maximum shutter opening degree from the exposure duration at 18fps. But:

a) Most manufacturers don’t list the real value in the manual. Instead you can find the nearest value that can be found on most exposure meters.

b) Besides the shutter, there can be other parts of the camera that reduce the amount of light that actually reaches the film. (E.g. many Super8-cameras are using semi-transparent mirrors for their SLR viewfinders. This prevents the viewfinder from turning black while a frame gets exposed.) Some manufacturers are taking this account when creating such exposure times tables.

Edited January 31, 2023 by Joerg Polzfusz