Jump to content


Photo

long exposure shots


  • Please log in to reply
15 replies to this topic

#1 Robert Gardner

Robert Gardner
  • Basic Members
  • PipPip
  • 57 posts
  • Camera Operator
  • Doha, Qatar

Posted 22 November 2007 - 10:48 AM

hi there,

i had a technical question of how to create slow shutter speed shots on film or video?
i used to take lots of city portraits by night with a very slow shutter speed so that all the traffic looks like different color lines. i was wondering how to create an effect like that on video or film? is it done in the camera or in post? have a look at attachments.
thanks for your thoughts,
rob

Attached Images

  • sample2.jpg
  • sample.jpg

  • 0

#2 Robert Houllahan

Robert Houllahan
  • Sustaining Members
  • 1582 posts
  • Industry Rep
  • Providence R.I.

Posted 22 November 2007 - 01:31 PM

hi there,

i had a technical question of how to create slow shutter speed shots on film or video?
i used to take lots of city portraits by night with a very slow shutter speed so that all the traffic looks like different color lines. i was wondering how to create an effect like that on video or film? is it done in the camera or in post? have a look at attachments.
thanks for your thoughts,
rob



You just need a camera which can be run with a long shutter duration, I have an eyemo with the revolution animation motor and i can program the motor to hold the shutter open i.e. 1 sec duration shutter2 sec interval or run at 1, 2 ,3 fps should get the streak you want. Depends on the speed of the motion, etc.

-Rob-
  • 0

#3 Robert Gardner

Robert Gardner
  • Basic Members
  • PipPip
  • 57 posts
  • Camera Operator
  • Doha, Qatar

Posted 23 November 2007 - 09:20 AM

You just need a camera which can be run with a long shutter duration, I have an eyemo with the revolution animation motor and i can program the motor to hold the shutter open i.e. 1 sec duration shutter2 sec interval or run at 1, 2 ,3 fps should get the streak you want. Depends on the speed of the motion, etc.

-Rob-


thanks rob,

so would i get the same effect with a film camera running it at 2fps? it would not only speed my footage up a lot but also give me those streaks of light?
cheers,
rob
  • 0

#4 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 23 November 2007 - 11:42 AM

thanks rob,

so would i get the same effect with a film camera running it at 2fps? it would not only speed my footage up a lot but also give me those streaks of light?
cheers,
rob


It's simple math -- a camera running at 2 fps with a 180 degree shutter has a per-frame exposure time of 1/4 of a second, which will make fast motion streak. Run it at 2 fps for normal speed and it will be somewhat "steppy".
  • 0

#5 Alessandro Machi

Alessandro Machi
  • Sustaining Members
  • 3318 posts
  • Other
  • California

Posted 23 November 2007 - 12:10 PM

hi there,

i had a technical question of how to create slow shutter speed shots on film or video?
i used to take lots of city portraits by night with a very slow shutter speed so that all the traffic looks like different color lines. i was wondering how to create an effect like that on video or film? is it done in the camera or in post? have a look at attachments.
thanks for your thoughts,
rob


There is a distinction to be made between stationary time-exposure shots and time-exposure shots from moving vehicles.

Generally shots from a stationary location require longer duration times, from 1-2 seconds on the fast end to anywhere from 5-6 seconds or more, depending on your framing and distance from the objects you filming.
  • 0

#6 Nick Mulder

Nick Mulder
  • Basic Members
  • PipPipPipPip
  • 1023 posts
  • Other
  • Auckland, New Zealand

Posted 23 November 2007 - 08:25 PM

The way to get long motion streaks but with time running near normal (so motion footage isn't just a jarbled mess which you may or may not want) would be to have a few (quite a few actually) cameras running through the same lens (someone else can design the prism for that!) but synced consecutively out of phase with each other ...

Each stream would give you the jarbled mess but it could be put together in post as a coherent stream ...

for example:

1.0 - 2.0 - 3.0 - 4.0 (cam1)
1.1 - 2.1 - 3.1 - 4.1 (cam2)
1.2 - 2.2 - 3.2 - 4.2 (cam3)
1.3 - 2.3 - 3.3 - 4.3 (cam4)
etc...

becomes>

1.0 - 1.1 - 1.2 - 1.3 .... 2.0 - 2.1 - 2.2 - 2.3 .... 3.0 - 3.1 - 3.2 - 3.3 etc...


the 'streams per cycle' could be anything you choose thereby giving you control of the relative duty cycle (which is one and the same as the length of the streak) - duty cycles exceeding %100 could be done, so in effect you are seeing into the future (sort of) within each frame

geddit ? heh

Might be better achieved with 1 sensor somehow - I'll let the digital video guys answer how that could be done. The data outputs per frame would 'overlap' themselves ...
  • 0

#7 Alessandro Machi

Alessandro Machi
  • Sustaining Members
  • 3318 posts
  • Other
  • California

Posted 23 November 2007 - 09:00 PM

If the camera is locked off then multiple frames can be overlapped in edit.
  • 0

#8 Nick Mulder

Nick Mulder
  • Basic Members
  • PipPipPipPip
  • 1023 posts
  • Other
  • Auckland, New Zealand

Posted 24 November 2007 - 03:24 AM

If the camera is locked off then multiple frames can be overlapped in edit.


You still will have missing information as with one (film) camera you couldn't have a 360deg shutter angle... But you're correct in that its a pretty convincing effect.
  • 0

#9 boy yniguez

boy yniguez
  • Basic Members
  • PipPip
  • 92 posts
  • Cinematographer

Posted 25 November 2007 - 02:25 AM

hi there,

i had a technical question of how to create slow shutter speed shots on film or video?
i used to take lots of city portraits by night with a very slow shutter speed so that all the traffic looks like different color lines. i was wondering how to create an effect like that on video or film? is it done in the camera or in post? have a look at attachments.
thanks for your thoughts,
rob



it is a whole lot more difficult to execute on film but in video there are consumer handicam models that have slow shutter settings that will give you those streaks but keeping motion normal!
  • 0

#10 Daniel Sheehy

Daniel Sheehy
  • Basic Members
  • PipPipPipPip
  • 407 posts
  • Other
  • Brisbane

Posted 25 November 2007 - 06:44 PM

it is a whole lot more difficult to execute on film but in video there are consumer handicam models that have slow shutter settings that will give you those streaks but keeping motion normal!

They simply use a slower shutter speed. Without a corresponding adjustment of the frame rate, it comes off looking stuttery... I wouldn't quite call that normal. :huh:
  • 0

#11 Robert Gardner

Robert Gardner
  • Basic Members
  • PipPip
  • 57 posts
  • Camera Operator
  • Doha, Qatar

Posted 26 November 2007 - 09:44 AM

Thanks a lot for all your suggestions. Helped me a lot!
Cheers,
Rob
  • 0

#12 boy yniguez

boy yniguez
  • Basic Members
  • PipPip
  • 92 posts
  • Cinematographer

Posted 29 November 2007 - 02:22 AM

They simply use a slower shutter speed. Without a corresponding adjustment of the frame rate, it comes off looking stuttery... I wouldn't quite call that normal. :huh:


daniel, you don't seem to understand video! in video you can not adjust frame rates from the 30 fps (NTSC). the slow shutter setting is done electronically such that there is no corresponding change in frame rate unlike that of film.
  • 0

#13 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19759 posts
  • Cinematographer
  • Los Angeles

Posted 29 November 2007 - 03:22 AM

daniel, you don't seem to understand video! in video you can not adjust frame rates from the 30 fps (NTSC). the slow shutter setting is done electronically such that there is no corresponding change in frame rate unlike that of film.


Sure you can -- you have no choice actually.

It is physically impossible for a camera shooting 30P to have a per frame exposure time longer than 1/30th of a second, just as it is physically impossible for a camera shooting at 60i to have a per field exposure longer than 1/60th of a second. If the camera is capturing 60 images per second as fields, the sensor is charging and discharging 60 times per second, the sensor can't have exposure times longer than 1/60th, not without breaking the laws of space and time.

Video cameras that offer long exposure times have to slow down the capture rate to do this, store this in a buffer, and then essentially write this information as normal video speeds for recording. But the effect is still stuttery just as a film camera running slower because there are fewer motion samples per second.

Think about it, if your NTSC video camera is capturing 60 fields every second, how could each field be exposed for times like 1/4 of a second? You can only capture 4 fields every second if each field was being exposed for 1/4 of a second.
  • 0

#14 John Sprung

John Sprung
  • Sustaining Members
  • 4635 posts
  • Other

Posted 29 November 2007 - 01:54 PM

While it is impossible to get exposure times longer that the frame or field period, it should be possible in post to get the streaking or motion blur effect of even longer exposures.

Suppose we shoot 24p with a 360 degree shutter. Make output frame #1 by superimposing camera frames 1 through 8 inclusive. Output frame #2 comes from camera frames 2-9, output #3 from camera 3-10, etc. Every output frame gets 1/3 second worth of motion blur, even though they're only 1/24 second apart. Shown at 24 fps, the motion is at its real speed, but the blur is huge. The 360 degree shutter is absolutely essential so we get continuous streaks, not streaks with seven gaps in them.

Remember again that this gets you the look of 1/3 second exposures, it doesn't get you any more light. You still have only 1/24 sec worth of light.



-- J.S.
  • 0

#15 Daniel Sheehy

Daniel Sheehy
  • Basic Members
  • PipPipPipPip
  • 407 posts
  • Other
  • Brisbane

Posted 29 November 2007 - 03:46 PM

daniel, you don't seem to understand video! in video you can not adjust frame rates from the 30 fps (NTSC)...

On the contrary. There are several video cameras available these days that offer not only variable shutter speeds, but variable frame rates as well. Off the top of my head I can think of 3 manufacturers who offer variable frame rates... Panasonic, Sony & RED.
  • 0

#16 Rainer Halbich

Rainer Halbich

    New

  • Basic Members
  • Pip
  • 6 posts
  • Camera Operator

Posted 14 January 2008 - 07:03 PM

Hi there.

I was in Capetown the other day and I did a long exposure shot from table mountain down on the city, Amazing!
I have this amazing brain flash but I don't want to share it with anyone, My e mail address is rainerfilm@gmail.com if you want to know.
  • 0


Opal

Broadcast Solutions Inc

Rig Wheels Passport

Wooden Camera

FJS International, LLC

Willys Widgets

Glidecam

Technodolly

Tai Audio

Aerial Filmworks

Gamma Ray Digital Inc

CineTape

Visual Products

CineLab

Abel Cine

Ritter Battery

rebotnix Technologies

The Slider

Metropolis Post

Paralinx LLC

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc

CineTape

Paralinx LLC

The Slider

Visual Products

Opal

Tai Audio

Abel Cine

Aerial Filmworks

FJS International, LLC

Willys Widgets

Broadcast Solutions Inc

Technodolly

Wooden Camera

Ritter Battery

rebotnix Technologies

Glidecam

Metropolis Post

CineLab

Rig Wheels Passport

Media Blackout - Custom Cables and AKS