Hi,

I've just received my Sony EX1, and I have seen that I'm not in control over the Shutter Angle. Can anyone tell me what the visible difference is if you change it, why you would change it, and what would be the best option if you are going for a filmic narrative look?

Thank you very much in advance,

I've read some trough the boards... If I'm correct, for a more filmic look I should go with the 180 degree shutter angle?

I've read some trough the boards... If I'm correct, for a more filmic look I should go with the 180 degree shutter angle?

That's the normal angle. If shooting 24P, it equates to 1/48 second. The 180 degree number comes from the mechanical shutter on the front of a film camera that rotates two revolutions for each frame of film. The circle is half open/half closed (180 degrees of a circle). Each film frame gets exposed twice at a 1/48 second differential in time.

Again, that's just for the standard rate. Other combinations are possible.

-gb-

>>>mechanical shutter on the front of a film camera that rotates two revolutions for each frame of film<<

No it doesn't; you are thinking of a projector, which has two openings per revolution. In a film camera the essential function of the shutter is to be closed while the film is advanced. In a simple mechanism the film is advanced during one half revolution of the shutter shaft, so the other half is available for exposure. So at 24fps the drive is running at 24 rps, hence 1/48 second. Often smaller shutter angles are used.

If you're not accustomed to using shutter angles (ie a film cinematographer) switch the EX to exposure time (1/48, 1/60, etc).

Yes, as Serena implies "shutter angle" is just another way of describing "shutter speed" for they both equate to length of each exposure. 180 deg is half of a full circle and means you get 50% of the maximum of if the shutter were always open so with 24p that equates to a shutter speed of 1/48.

Setting your shutter speed to 1/48th with 24p is exactly the same as setting the shutter angle to 180.

IF with 24p you wanted to double the exposure so you had the full 1/24th of a second for every frame of the 24, IE a shutter angle of 360deg, then you just turn the shutter OFF with the little slider switch near the white balance button on the front of the camera.

Mike

I know this is trivial, but Panaflex cameras have used a shutter with two openings, the mirror segments are 80 degrees wide and placed opposite each other which means the mirror only has to spin half as fast, and allows for a 200 degree shutter.

-Sean

So shutter "angle" does or does not mean that the sensor is read out in a way that simulates the exposure which results from the REVOLVING sector of a film camera?
Can anyone please confirm this.

>>>mechanical shutter on the front of a film camera that rotates two revolutions for each frame of film<<

No it doesn't; you are thinking of a projector, which has two openings per revolution. In a film camera the essential function of the shutter is to be closed while the film is advanced. In a simple mechanism the film is advanced during one half revolution of the shutter shaft, so the other half is available for exposure. So at 24fps the drive is running at 24 rps, hence 1/48 second. Often smaller shutter angles are used.

Mea culpa. Here's a wiki link that explains and animates it.

http://en.wikipedia.org/wiki/Rotary_disc_shutter

-gb-

Michael,

Yes, that's what it means. It uses the same convention as a revolving shutter film camera (not a projector as Serena correctly pointed out).

180/360 = 1/2

Half of the frame time is spent exposing the sensor/film. The other half is blanked.

So at 24fps, (a frame exposed every 1/24 second) 180° shutter, the exposure is 1/48 second.

Greg, Eric, I think there is still a misunderstanding:
Are you sure the sensor is read out exactly the way a rolling shutter exposes a frame (angular direction from top left to bottom right corner of the sensor)?
Or is it just a normal linear read out instead (straight horizontal or vertical movement) - the way the shutter of a SLR exposes a frame?

Greg, Eric, I think there is still a misunderstanding:
Are you sure the sensor is read out exactly the way a rolling shutter exposes a frame (angular direction from top left to bottom right corner of the sensor)?
Or is it just a normal linear read out instead (straight horizontal or vertical movement) - the way the shutter of a SLR exposes a frame?

It is read out linearly, definitely. From top to bottom of the image (bottom to top of the sensor)

The shutter angle is just a convention used to refer to the proportion of time open to time closed per frame.

BTW, there is no set convention for shutters on film cameras. Most Arris have the spinning shutter below the gate, while Panavisions usually sit to one side of the gate. This yields very different sweep patterns over the film plane.

http://en.wikipedia.org/wiki/Rotary_disc_shutter

Thanks, Paul and Eric, for the clarification.
Yes, it was the "sweep pattern" of the EX1' sensor read out that I was interested in.

http://en.wikipedia.org/wiki/Rotary_disc_shutter

Hehe. Paul, I posted that same link just above.

-gb-

The real reason you would want to use the shutter angle on the EX1 is for variable frame rates. By setting it to 180 degrees you will guarantee the correct shutter for good slow motion no matter which framerate you use. Otherwise you would have to calculate things manually (and there isn't enough selections of fractions of a second style shutter to account for every frame rate combination anyway). So in short, use fractions of a second for normal shooting, and shutter angle for variable frame rate.

So the term Shutter ANGLE is just a hold over from film?

On the EX1, SHUTTER ANGLE is really just a multiplier of shutter speed? 180 shutter angle makes the shutter speed twice as fast as the frame rate, regardless of the frame rate?

In a film camera, if the exposed area is a rotating wedge of light, it seems that would affect the image of a fast moving object.

is there any equivilant affect in video?

The Arri D20 has a mechanical shutter as do some of the Dalsa's. This allows for the use of an optical viewfinder.

The real reason you would want to use the shutter angle on the EX1 is for variable frame rates. By setting it to 180 degrees you will guarantee the correct shutter for good slow motion no matter which framerate you use. Otherwise you would have to calculate things manually (and there isn't enough selections of fractions of a second style shutter to account for every frame rate combination anyway). So in short, use fractions of a second for normal shooting, and shutter angle for variable frame rate.

Thanks for that useful piece of info Simon. Takes it from the academic to the useful when using electronic cams.

The real reason you would want to use the shutter angle on the EX1 is for variable frame rates. By setting it to 180 degrees you will guarantee the correct shutter for good slow motion no matter which framerate you use. .

Okay so 180 ensures proper shutter for slo mo. Why isn't it always set to 180? What are the the circumstances you DON'T want 180?

There are 2 ways to control exposure: iris and shutter (putting aside filters and gain). So if you want to use a large iris (for shallow DOF) then you have to reduce shutter opening. Other reasons are to reduce flicker of AC lighting, freezing motion, and conversely blurring motion. Also long exposures. The reason for having shutter angle on XDCAM is that many DPs are used to film cameras where shutter angle is the relevant parameter. People who have never used film are used to shutter open time. Not magic, just convenient options.

There are 2 ways to control exposure: iris and shutter (putting aside filters and gain). So if you want to use a large iris (for shallow DOF) then you have to reduce shutter opening. Other reasons are to reduce flicker of AC lighting, freezing motion, and conversely blurring motion. Also long exposures. The reason for having shutter angle on XDCAM is that many DPs are used to film cameras where shutter angle is the relevant parameter. People who have never used film are used to shutter open time. Not magic, just convenient options.

Is there a chart somewhere that shows when to use a particular shutter angle and under what circumstances?

There are 2 ways to control exposure
There's a third very important one: nd-filter
And there's fourth not so great one: gain
Is there a chart somewhere that shows when to use a particular shutter angle and under what circumstances?
Generally use for 24/25/30fps 180° and for 50/60fps (playback-rate) 360° (= shutter off). For achieving a dramatic stroboscope/adrenalin-effect (known from saving private ryan, some hiphop-video-clips,...) use smaller angles. This effect doesn't work with 50/60fps.

[QUOTE=Dominik Seibold;975031]
Generally use for 24/25/30fps 180° and for 50/60fps (playback-rate) 360° (= shutter off).
/QUOTE]

Okay but a few posts up someone else is saying the 180 degree works best for slo mo. Who doya believe?? what's the real story?

Okay but a few posts up someone else is saying the 180 degree works best for slo mo. Who doya believe?? what's the real story?
That's why I mentioned "playback-rate". If you're recording 60fps for playing back with 25fps, use 180. If playing back with 60, use 360. It's all about the playback-rate, not the recording-rate, because it's about serving our visual system (eyes+brain).

There's a third very important one: nd-filter
And there's fourth not so great one: gain

Seems to me that I mentioned those too. But people seldom read what is written!