Shutter Angle on a Butterfly Shutter: 180 and 172.8 Degrees

[Kapil Raj]

How it's possible to have 180 degree shutter angle in a Butterfly shutter?
Also in the case of 172.8 degree?
What's the maximum degree of shutter angle we can go for in a butterfly type shutter?
It will be thankful if anybody explain with diagrams.

 

[laurent.a]

What is a butterfly shutter? Is it a bipale one? If so, you have 2 angles instead of 1. Just have each of them at 90°, it makes the whole aperture being 180°.

If you have one at 90 ° and you can set the other as you like, it's not a problem setting it at 82.8 so that the whole aperture is 172.8.

 

[Kapil Raj]

shutter angle more queries

shutter angle more queries

If it is 90 degree what will be the exposure which each frame will get?
How a single frame will get a total 180 degree shutter angle?
What happens when the shutter is in closed position after the first 90 degree? Whether the film moves or steady?
Is every single frame is double exposed?
What will be the shutter speed?
What is the possibility of using an exposure meter where all the exposure meters which is meant for motion picture photography will gives an exposure for 180 degree shutter angle?
Is there any reflex camera which is having disc type shutter?

 

[laurent.a]

Actually I know of bipale/two blades shutters for projection only. I don't know if any camera is equipped with such a shutter. The 172°8 angle would have no sense, then.

I'd really need to know where you found that, in what context.

 

[Brad Hoover]

Butterfly Shutter

Butterfly Shutter

Each blade of a butterfly shutter (as is used in most Arri cameras) is only 90 degrees. However, the butterfly shutter revolves at half the speed of a pie plate or focal plane shutter, thus the blade covers the aperture for twice as long as a regular 180 degree shutter resulting in an exposure of 1/48th of a second at 24 FPS. This arrangement also reduces camera noise and vibration as the butterfly shutter is perfectly balanced and does not have to spin as fast.