Jump to content


shutter angle


  • Please log in to reply
4 replies to this topic

#1 mnpd

mnpd
  • Guests

Posted 28 September 2005 - 11:54 AM

Could somebody tell me what effect the shutter angle has on an image ?

many Thanks

Tony :)
  • 0

#2 John Pytlak RIP

John Pytlak RIP

    (deceased)

  • Sustaining Members
  • 3499 posts
  • Industry Rep
  • Rochester, NY 14650-1922

Posted 28 September 2005 - 01:12 PM

Could somebody tell me what effect the shutter angle has on an image ?

many Thanks

Tony :)

<{POST_SNAPBACK}>


In simple terms, the shutter angle is directly related to the exposure time of each frame. A longer exposure time gives more "motion blur", a very short exposure time gives an image with less motion blur, but may be perceived as more "strobey".

For a 180 degree shutter opening at 24 frames per second, the exposure time of each frame may be calculated:

(180/360) x (1/24) = 1/48 second

If you are panning, or have action in the scene, whatever movement there is in 1/48 second will show as a blur in the image. Most people are very used to the motion blur of film shot at 24fps and a shutter opening near 180 degrees, and perceive other exposure times as somewhat "unnatural" or "disconcerting", e.g., when used for effect in "Saving Private Ryan" or "The Gladiator".
  • 0

#3 mnpd

mnpd
  • Guests

Posted 29 September 2005 - 04:07 AM

In simple terms, the shutter angle is directly related to the exposure time of each frame.  A longer exposure time gives more "motion blur", a very short exposure time gives an image with less motion blur, but may be perceived as more "strobey".

For a 180 degree shutter opening at 24 frames per second, the exposure time of each frame may be calculated:

(180/360) x (1/24) = 1/48 second

If you are panning, or have action in the scene, whatever movement there is in 1/48 second will show as a blur in the image.  Most people are very used to the motion blur of film shot at 24fps and a shutter opening near 180 degrees, and perceive other exposure times as somewhat "unnatural" or "disconcerting", e.g., when used for effect in "Saving Private Ryan" or "The Gladiator".

<{POST_SNAPBACK}>


Thanks John :)
  • 0

#4 Dimitrios Koukas

Dimitrios Koukas
  • Sustaining Members
  • 569 posts
  • Cinematographer
  • Athens, Greece, London UK

Posted 29 September 2005 - 06:20 AM

In simple terms, the shutter angle is directly related to the exposure time of each frame.  A longer exposure time gives more "motion blur", a very short exposure time gives an image with less motion blur, but may be perceived as more "strobey".

For a 180 degree shutter opening at 24 frames per second, the exposure time of each frame may be calculated:

(180/360) x (1/24) = 1/48 second

If you are panning, or have action in the scene, whatever movement there is in 1/48 second will show as a blur in the image.  Most people are very used to the motion blur of film shot at 24fps and a shutter opening near 180 degrees, and perceive other exposure times as somewhat "unnatural" or "disconcerting", e.g., when used for effect in "Saving Private Ryan" or "The Gladiator".

<{POST_SNAPBACK}>


Also there is a relation to the direction of pan,
so there is a bigger issue when you re panning opposite the subjects direction.
One thing to do, is to shoot with a bigger frame rate like 50 fps or 35fps, when u are having for example a train moving close to your lens and towards left side of your frame.
If it doesn't make sense, cause of my lack of explainning things, I could try more if you have any questions.
Dimitrios Koukas
  • 0

#5 Fran Kuhn

Fran Kuhn
  • Sustaining Members
  • 352 posts
  • Other

Posted 29 September 2005 - 03:22 PM

In addition to the staccato "Private Ryan" effects created by narrower-than-normal shutter angles, there is another cool use for shutter angle adjustment. When shooting subjects a that are not moving, say a locked-off shot of a car parked on a dry lake in the desert, you can sometimes vary the shutter angle to allow for more (or less) exposure time to be given to each frame. It might allow you to get to the particular t-stop for the look you desire.

Lets say your film stock is 250 ASA and you're shooting the new Sweet Crude Black H3.5 Hummer in bright sunlight at high noon. (I know--you're thinking, "High noon light on sheet metal?" But in case you haven't noticed, Ugly is the new Beautiful in automotive this season.)

A straight meter reading says t45 at 24fps, but you want to get to t8 to get a shallower depth-of-field. So you put, lets say, a neutral density 0.9 (minus 3 stops) filter on and now you can shoot at t16, but you're still two stops away from the magic t8. If you're out of neutral density, you could decrease the film's exposure time by two stops by increasing the camera's frame rate by four times to 92fps, but say the particular camera you're using won't go past 50fps even with a full wind on the spring. But if the camera's shutter is adjustable, you could instead narrow the shutter from the normal 180 degrees to just 45 degrees. This narrow 45-degree angle will cut the amount of time the film gets hit by the blazing desert sun by two stops: 90 degrees being half of 180 (there's one stop) and 45 is half of 90 (there's the second stop). So you can now open up to t8 on the lens and go crack open a cold one with the client while your First shoots that overpriced soccer-mom-hauling gas-guzzler.

Since the shot is locked off and in theory nothing is moving, you wouldn't notice the narrow shutter effect. But watch out if you have palm fronds blowing around in the background! Of course, you could always say that you planned the freaky background motion all along. Maybe the creatives will buy it. "He a genius--we have to shoot the entire campaign at 45-degrees!"

Just wait. . .someone's gonna try it.
  • 0


Aerial Filmworks

The Slider

FJS International, LLC

Paralinx LLC

Broadcast Solutions Inc

Visual Products

CineTape

Glidecam

Rig Wheels Passport

Opal

Abel Cine

Tai Audio

Metropolis Post

Technodolly

Ritter Battery

Wooden Camera

Willys Widgets

CineLab

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc

rebotnix Technologies

Tai Audio

Media Blackout - Custom Cables and AKS

Glidecam

Willys Widgets

Gamma Ray Digital Inc

Aerial Filmworks

FJS International, LLC

Wooden Camera

Opal

CineLab

Technodolly

Metropolis Post

Rig Wheels Passport

rebotnix Technologies

Visual Products

The Slider

Paralinx LLC

Ritter Battery

Broadcast Solutions Inc

Abel Cine

CineTape