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How do I achieve this effect in a motion picture camera


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#1 Blake

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Posted 16 March 2006 - 07:35 PM

Hello all

I am trying to find out how I can achieve a similar effect to this photo (link below), but on super 16mm film, I want to film cars driving along the motorway at night.

http://thecreativefo...ll_IMG_0006.JPG

I understand how to do it with a normal stills camera, but not sure how to do it with a motion camera.

Would it just be a digital effect that I apply afterwards.

Any ideas, would be most appreciated.

Edited by Blake, 16 March 2006 - 07:36 PM.

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#2 Dominic Case

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Posted 16 March 2006 - 09:02 PM

There's no way you can get exactly this effect directly in a film camera. Some post work is needed.

I presume what you want is not just a freeze frame showing the motion streaks, but live action where the motion has a long tail. In other words you would see headlights passing along the road, leaving a trail behind that would eventually fade out after a certain number of frames. Slower moving objects would leave shroter trails.

This used to be quite easy on an optical printer: and I believe you can find tools in digital imaging software that will do the same thing. Simply, each frame of the camera original has to be repeated a number of times, each with a fraction of the exposure (or level), reducing over the last few frames.

It's easiest to explain a frame in the middle of the sequence: frame 8 of your output would be a composite of frames 1-8 of the original material. Frame 9 would be frames 2-9, frame 10 would be frames 3-10 etc. In an optical printer each of those frames would be given 1/8th normal exposure: in digital, each would be at 1/8th level. (You'd vary those numbers to get a fade out).
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#3 Phil Rhodes

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Posted 16 March 2006 - 09:37 PM

Hi,

After Effects has a filter called "ghosting" that approximates this effect.

Like most post effects, it's better when composited into the shot with custom tweaks - to get what you're after, you'd probably want the highlights to streak more than everything else, so you'd comp a duplicate of your shot back over the original with the appropriate levels settings.

You can also do this in a bullet-time still camera array scenario, because you can then have an exposure time that's longer than the notional frame rate, if that makes sense. It was done for a cellphone ad in the UK. Drawing a shape in mid air with a flashlight during a long exposure in a blacked-out studio produces a hovering, glowing, three-dimensional figure which you can move around and view from different angles - it's quite beautiful.

Phil
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#4 Matthew Skala

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Posted 17 March 2006 - 10:36 AM

Hello,

The bullet time camera array seems like your best option but also the most expensive. The only way to do it in camera would be to do a timelapse sequence with shutter angle open as far as it can go and at the slowest frame rate possible or use interval shooting.

On "Domino" they shot a lot of stuff at 6 frames a second and printed it at 6 frames a second. the result was stuttered motion but with some really interesting motion blur. I am not sure what the shutter angle setting was but it was probably as far open as they could get it.

And you can even do this with one still camera to get maximum amount of blur. You would have to be consistent and calculate a consistant time between each shot. The only problem though, is it will be timelapse.

For example, you can take 1 picture every 30 seconds. Or you can try shooting one after another (the function where you hold the shutter down and click, click, click... ) using a slow shutter speed. This is something you would have to experiment with and of course use a tripod.

Please post results. Would love to know how it goes.
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#5 Charles MacDonald

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Posted 17 March 2006 - 10:01 PM

There's no way you can get exactly this effect directly in a film camera. Some post work is needed.
Simply, each frame of the camera original has to be repeated a number of times, each with a fraction of the exposure (or level), reducing over the last few frames.

It's easiest to explain a frame in the middle of the sequence: frame 8 of your output would be a composite of frames 1-8 of the original material. Frame 9 would be frames 2-9, frame 10 would be frames 3-10 etc. In an optical printer each of those frames would be given 1/8th normal exposure: in digital, each would be at 1/8th level. (You'd vary those numbers to get a fade out).

I hate to disagree with a master, Dominic, but since the shutter on the camera is closed while the film is moved to the next frame, the streaks would look dotted if printed as you propose.. Each frame wold have some of the streak from the moving lights but the light from when the shutter was closed would be lost. If the car was moving slow enough this might not be obvious.

The "Bullet Time" method whould allow a real 30 SECOND or more exposure for each frame, although you would need to have a "virtual Dolly" as you can't get all the cameras in exactly the same spot.

When I tried to get this sort of shot years ago with a still camera I used 100 ASA slide film, and f/16 for one cycle of the trafic lights..

Edited by Charles, 17 March 2006 - 10:02 PM.

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#6 David Mullen ASC

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Posted 17 March 2006 - 10:18 PM

This would be done with a time-lapse camera and a long per-frame shutter speed. Of course, the cars will look sped-up at 24 fps playback.

Years ago, I got a similar effect by cranking up DVNR (digital video noise reduction) in a telecine suite transferring normal-speed night footage -- the lag that comes from sampling and overlaying surrounding frames to reduce grain creates this streaking effect when set to incredibly high levels.
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#7 Michael Collier

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Posted 17 March 2006 - 10:25 PM

you mentioned using bulet time technique, but that would force a virtual dolly. my question is why? i know that if you wanted to make the effect of long highlight tails on real time footage, then yes you would have multiple cameras exposing at the same time. but if all you want is the tails and you are ok with having everthing be in super-fast speed (as most shots like these are) then you only need one still camera. set the shutter to 30 seconds, or around there for the speed you want in the end, and expose. wait about 5-10 seconds and expose the second one. since virtually everything in frame will clear frame before the 30 second exposure is up, motion and stutter is no concern. that 10 seconds it is not exposing is not needed, because at this exposure length, every frame will be different from eachother.


but i know nothing of intervolometers, i know the a-minima even when doing time lapse is restricted to a certain exposure time, i think 1/45 of a second, as it has a 178.2 degree shutter. some film cameras may allow you to expose 30 seconds then transport to next frame, then expose again. more experienced film people than i can elaborate.

if you go with using after effects ghosting filter, make sure you shoot without any kind of shutter. the ghosting will be broken up and you wont get the exact same look. same idea, but you wont get the long continuous beam of light.

now if you want to have the long streaks, but also need everything in frame moving in real time, then bullet time effect is the only choice, and with that option a new camera would expose every 1/48th of a second, but each one would stay open for 10-30seconds to provide the long shutter effect.
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#8 Dominic Case

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Posted 20 March 2006 - 02:26 AM

I hate to disagree with a master, Dominic, but since the shutter on the camera is closed while the film is moved to the next frame, the streaks would look dotted if printed as you propose..

You are absolutely right, Charles. Nevertheless, before digital effects, I think that is how this effect would have to have been done. It's the closest possible approach to the still camera effect.

You could mitigate the "dotted lines" by a wider shutter angle: and if the lights are bright enough (and slow enough as you suggest), some flaring might also blur the dots together.

A faster frame rate would also make for smaller gaps between the dots (therefore easier for the blurs to join up).

As you point out, the bullet time technique would imply a slight dolly effect, so that's a compromise too. And the original question was "how do I do this on super 16 film?".

Still, interesting to read the creative discussion about how others would solve this, given different constraints.
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#9 Freya Black

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Posted 20 March 2006 - 06:34 AM

Is this not just a normal time exposure effect that you could get with a camera on auto B?

I thought that the bolex h16 was able to do time exposure somehow?

In a timed exposure camera the shutter is kept open for varying amounts of time depending on how little light there is. It's an interlavometer style function.

Maybe I have misunderstood exactly what you guys are talking about however.

love

Freya

Edited by Freya, 20 March 2006 - 06:37 AM.

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#10 Freya Black

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Posted 20 March 2006 - 06:55 AM

Okay, I searched the archive and found this:

Yes, that's correct.
All Bolex H16 have that feature. On models before the mid-60's, it's a little lever switch with 'I/T' inscribed. I is the fixed shutter speed setting for single frame shots (check your manual for exposure time, as it depends on camera models), and the T setting is for a manually controled single-frame exposure : press the side release and the shutter opens, release is to close the shutter.
On later models (from the Rex/M/S-4 on), the switch becomes a small rotating button, but the function is exactly the same.
This feaure can also be used in conjunction with an appropriate single-frame motor.
Great stuff !
-B


It is only a bulb feature not an auto bulb feature but it could still do the trick! :)

I'm not sure how this would work in practice however because I'm not sure if this would work with a normal cable release or if the interlavometer would be able to hold the frames open for long enough.

Also having re-read the thread I realise you guys seem to be trying to get this effect in real time but I suppose you could slow the resulting footage down to real time, perhaps with an optiical printer like Dominic suggests. It might look a bit staccato tho. Perhaps this could be a job for twixtor? :)

[I notice on re-reading, that cinephile suggests the same thing preety much, I'm losing my reading skills or something. Maybe I need a nap]

love

Freya

Edited by Freya, 20 March 2006 - 07:01 AM.

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#11 Charles MacDonald

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Posted 20 March 2006 - 07:52 PM

Okay, I searched the archive and found this:
It is only a bulb feature not an auto bulb feature but it could still do the trick! :)


As I read the original question, I assumed the effect desired would be to have the car moving in (appernt) real time with the taillights streaking behind.

If you just take a seies of time exposures the cars will be jumping randomly arround ... (I have seem that effect in a TV commercial once so it is a valid thing to try)

One thought I had if the shot is really at night, so the sky changing colour would not happen (or shot in a studio) would be to do stap frame animation, and have the car drive down the road over and over, with the shutter tripped a little further on each time.

That would also let you fire a flash just beofore the shutter closed to give a little light ot make the car stand out clearly. The flash would be outsdde the frame and would be kept the same differnce from the car for each shot.

Maybe you could get "GUMBY" to drive the car?
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#12 Nick Mulder

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Posted 21 March 2006 - 05:58 AM

use two cameras, very close to each other (shooting telephoto probably) or through the same lens with a 50/50 beam splitter setup -

each cam filming at a rate half of your desired rate - have the shutter of each be open for as long as you can of the cameras rate - ie. have a long open duty cycle...

Have each camera 180deg out of phase with the other - shoot ...

in post take frame1 of cam1 them frame1 of cam2 then frame2 of cam1 then frame2 of cam2 and so on ...

very 'bolex' :rolleyes:

that would give your streaks a nice over lap frame to frame and a kind of weird past/future thing going on - if you have just the one cam to play with do the same but increase the frame rate (your streaks will be half as long)

see attached pix of duty cycle drive set up ...
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#13 Filip Plesha

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Posted 21 March 2006 - 08:42 AM

I really don't know why everybody is complicating this with digital effects and such things..

In motion, this would be a classic example of time lapse photography, or at least a very slow continuous
motion picture photography. Classic stock cinematography stuff.
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#14 Nick Mulder

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Posted 22 March 2006 - 05:17 AM

I really don't know why everybody is complicating this with digital effects and such things..

In motion, this would be a classic example of time lapse photography, or at least a very slow continuous
motion picture photography. Classic stock cinematography stuff.


Yep, + I think there are still very many effects to be pioneered that dont need to go digital ...

:ph34r:
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#15 Dominic Case

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Posted 23 March 2006 - 01:36 AM

I really don't know why everybody is complicating this with digital effects and such things..

In motion, this would be a classic example of time lapse photography, or at least a very slow continuous
motion picture photography.


Well not if the original brief was what most people have assumed - in other words, live action in real time at real speed, but with long tails to the lights. To achieve that, you'd need the long exposures that Filip says (maybe 1 or 2 seconds, probably not the 10 or 30 that others thought), but you'd need 24 of them per second, so that the leading and trailing ends of each streak move steadily at normal speed.

On one camera, that's an impossibility.

So you either need to superimpose lots of frames in post (digital or optical) - which was my solution - but that would give "dotted" streaks not continuous:

OR you need 2 cameras as Nick proposed ( beam splitter would eliminate any parallax issue) but you'd need some technique to get the two images perfectly aligned with each other:

OR you use the multiple camera "bullet time" approach, which could give you the desired 24 frames per second each with a 2-second exposure, but you'd need to accept the "virtual dolly" effect. And for a long sequence, you'd need each camera to expose a number of frames - 2 second exposures with a normal 1/48th sec pulldown - unlike the single-frame approach of the original "Matrix Effect" bullet time.
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#16 Charles MacDonald

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Posted 24 March 2006 - 09:27 PM

I thought of one other thing to try....

A defraction grating, if you can find one, I don't think that their is an equivelent of the stuff you used to be able to get from "edmound scientific" when I was a kid.

Problem is that it will make the car slightly blurry, and you have to watch the angle to avoid generating streaks "In front of" the taillights.
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#17 sinisa.kukic

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Posted 26 March 2006 - 11:14 PM

I did something similar to this a few years ago with a bolex and a intervelometer. shot a car driving down the road from a car driving along the side of it. i did one second exposures. took the film to optical printer and cross disolved through each of the frames. it looked interesting but not the same thing that all of you are talking about.

sinisa
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#18 Jamie Metzger

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Posted 29 March 2006 - 12:45 PM

pull out the rotating shutter.

see "Cheung Kink Express" or "Saving Private Ryan"
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#19 Chrisley Tjiputra

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Posted 29 March 2006 - 10:23 PM

OR you use the multiple camera "bullet time" approach, which could give you the desired 24 frames per second each with a 2-second exposure, but you'd need to accept the "virtual dolly" effect. And for a long sequence, you'd need each camera to expose a number of frames - 2 second exposures with a normal 1/48th sec pulldown - unlike the single-frame approach of the original "Matrix Effect" bullet time.


What do you mean? 24fps with 2 sec exposure?

I know that in 24fps mode, every second captures 24 frames. How is it possible to shoot 2 second
of exposure with 24fps?
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#20 Nick Mulder

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Posted 30 March 2006 - 08:43 PM

What do you mean? 24fps with 2 sec exposure?

I know that in 24fps mode, every second captures 24 frames. How is it possible to shoot 2 second
of exposure with 24fps?


You will need 24 cameras :lol:
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