Understanding and deciding on a shutter angle

[Dave Keen]

Hello!

I got a Canon 1014 Auto Zoom Super 8 camera. It has a variable shutter angle 0 to 150 degrees. Now why isn't 180 degrees available? For that matter, why wouldn't anything from 0-360 degrees be available?

It's got 18 fps, 24 and about 54 for slow motion. Can someone help me to decide how to properly understand and set my shutter angle on this cool old camera?

 

[Mark Dunn]

360 deg? You're thinking of digital. The shutter has to be closed to advance the film. 220 is usually the maximum for an XL model.

150 is a little narrow for a non-XL camera, 165 was more usual but you have what you have.

There's a manual here

https://www.pacificrimcamera.com/rl/00775/00775.pdf

Edited December 8, 2022 by Mark Dunn

[David Mullen ASC]

150 degrees might have just been the longest open the designers could manage.

Film cameras have to have a closed period to allow time to pull-down the film to the next frame before exposing it -- if you've ever seen footage with a mistimed shutter, a percentage of the exposure is streaked because the film was in motion before the shutter was completely closed. The film has to be static in the gate at the moment of exposure. 

[Dave Keen]

8 hours ago, Mark Dunn said:

360 deg? You're thinking of digital. The shutter has to be closed to advance the film. 220 is usually the maximum for an XL model.

150 is a little narrow for a non-XL camera, 165 was more usual but you have what you have.

There's a manual here

https://www.pacificrimcamera.com/rl/00775/00775.pdf

Thanks Mark,

Yeah been studying up on the whole thing today. I'll just shoot where it's best and make the most of it. Very fun.

[Joerg Polzfusz]

A smaller shutter angle means that the exposure duration is shorter. So, you’ll need more light. Hence, you’ll have to open the iris more wide (with the usual impact on the depth of field). But on the other hand, you’ll also have less motion blur.

 

The relatively small maximum shutter angle is most likely a result of the camera’s 54fps.

[Dave Keen]

5 hours ago, David Mullen ASC said:

150 degrees might have just been the longest open the designers could manage.

Film cameras have to have a closed period to allow time to pull-down the film to the next frame before exposing it -- if you've ever seen footage with a mistimed shutter, a percentage of the exposure is streaked because the film was in motion before the shutter was completely closed. The film has to be static in the gate at the moment of exposure. 

Thanks David,

Watched some videos on shutters so it makes more sense now. 

[Dave Keen]

1 minute ago, Joerg Polzfusz said:

A smaller shutter angle means that the exposure duration is shorter. So, you’ll need more light. Hence, you’ll have to open the iris more wide (with the usual impact on the depth of field). But on the other hand, you’ll also have less motion blur.

 

The relatively small maximum shutter angle is most likely a result of the camera’s 54fps.

Thanks Joerg,

 

Yes i see it has this switch to jump up to that 54 fps.

[Dom Jaeger]

Variable shutters on cameras like this were mainly for doing in-camera fade-ins and fade-outs. You can keep the same aperture setting (so depth of field remains the same), while reducing the amount of light hitting the film until it goes black. If you rewind the film a little, then do a fade-in you can get nice superimposed fades between shots. 

As others have mentioned, film cameras always need a period when the shutter covers the film while it gets moved to the next frame. A faster pulldown can allow for a larger shutter angle, but it requires a more sophisticated mechanism to avoid introducing instability, especially at higher frame rates. A lot of basic pulldown mechanisms just use a claw that pivots on a rotating cam, so the film is being pushed forward for around half the cycle. Add a little safety margin either side and you end up needing a shutter angle of around 150 degrees. 

You can use the variable shutter to change the look of the footage - a smaller shutter angle means a quicker exposure, more time between images and each image having less motion blur, so in playback motion appears more stuttery. 

You can also use the variable shutter as a way of controlling your aperture, to avoid being stopped all the way down on a sunny day, or to make your depth of field shallower. Reducing the shutter angle means you need to open up the aperture to compensate for less light hitting the film. But you only have 2 stops of adjustment and it does affect the look of motion, so ND filters are usually a better method for this.