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long exposure shots


Robert Gardner

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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

post-16242-1195746476.jpg

post-16242-1195746487.jpg

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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-

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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

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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".

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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.

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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 ...

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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.

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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!

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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:

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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.

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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.

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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.

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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.

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  • 1 month later...

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.

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