Jump to content


Photo

Water streak effect


  • Please log in to reply
7 replies to this topic

#1 George Ebersole

George Ebersole
  • Sustaining Members
  • 1525 posts
  • Industry Rep
  • San Francisco Bay Area

Posted 21 December 2016 - 11:36 AM

For mosters and time lapse shots there's an effect where falling water or water rushing over rocks gets all fuzzy, blurry and in general cool looking.

 

Has anyone tried to achieve this with digital video?

 

If so, how did you do it?


  • 0

#2 Macks Fiiod

Macks Fiiod
  • Basic Members
  • PipPipPipPip
  • 1089 posts
  • Director
  • Og from DC, Now in NJ

Posted 21 December 2016 - 12:01 PM

Link a sample of it?


  • 0

#3 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19644 posts
  • Cinematographer
  • Los Angeles

Posted 21 December 2016 - 12:46 PM

To get moving water like in a river to be streaked requires very long per-frame exposures, which isn't possible when the camera is running at 24 fps where even with a 360 degree shutter angle (no shutter at all) the max exposure time is therefore 1/24th of a second.  You'd have to shoot at a very low frame rate (like 2 fps, etc.) and then stretch it make to normal speed in post, but then the motion of people in the shot will also be blurred and very steppy due to the low sampling rate.


  • 0

#4 George Ebersole

George Ebersole
  • Sustaining Members
  • 1525 posts
  • Industry Rep
  • San Francisco Bay Area

Posted 21 December 2016 - 02:26 PM

Yeah, I thought it might require some post work, but I thought maybe someone had figured out a cheat or a workaround to get the same thing in camera.


  • 0

#5 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19644 posts
  • Cinematographer
  • Los Angeles

Posted 21 December 2016 - 02:39 PM

Heavy motion blur requires longer-than-normal exposure times.  Once you go to a 360 degree shutter angle, the only way to increase per-frame exposure time is to drop the frame rate.

 

The Canon XL1 DV camera had such a feature for low-light photography where they reduced the frame rate, got longer exposures, and internally restored the motion speed back to normal.


  • 0

#6 George Ebersole

George Ebersole
  • Sustaining Members
  • 1525 posts
  • Industry Rep
  • San Francisco Bay Area

Posted 22 December 2016 - 12:38 AM

And yet another reason I'm kicking myself for not buying a Canon.


  • 0

#7 Sarah Thompson

Sarah Thompson

    New

  • Basic Members
  • Pip
  • 5 posts
  • Cinematographer
  • Chicago

Posted 16 September 2017 - 01:44 AM

I haven't tried this, but I am pretty sure it would work:

1. Lock the camera down really solidly so there is no movement at all in terms of pan/tilt.
2. Shoot the scene at as close as possible to a 360 degree shutter angle.
3. Frame rate can be anything you like depending on the kind of movement you want.
4. In post (ideally in After Effects or Nuke, but I'll explain for After Effects), import the footage into a new comp. Create a black solid and put it below the footage. Set the footage layer to a low level of opacity and choose an additive blend mode. Then make a large number of copies of that layer and offset each of them in time by 1 frame. You'll need a LOT of them, enough to span 10 to 30 seconds depending on your frame rate.

This will effectively give you a 10 to 30 second exposure for the water, but with a rolling window so you still get movement.

If you have elements you don't want to blur, add another layer at the top of the stack set to normal blend mode and be prepared for some work because you will need to roto masks for them. Another option would be to shoot the live action separately from the water -- I'd keep the camera locked down between both shots, but for the live action I would go back to a 180 degree (or whatever your preference) shutter so the movement doesn't look weird and set up a portable popup green screen behind the actor(s). This would give better looking movement whilst letting you pull a key so most of the roto can be avoided.
  • 0

#8 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11879 posts
  • Other

Posted 16 September 2017 - 01:56 AM

I think you can probably make it do that with the time remapping, if you set the comp shutter angle to some suitably large value.


  • 0


Paralinx LLC

Metropolis Post

Visual Products

Broadcast Solutions Inc

Wooden Camera

Aerial Filmworks

Glidecam

Tai Audio

Ritter Battery

Media Blackout - Custom Cables and AKS

Willys Widgets

CineLab

Rig Wheels Passport

Gamma Ray Digital Inc

Abel Cine

rebotnix Technologies

FJS International, LLC

The Slider

Technodolly

CineTape

Paralinx LLC

CineLab

Rig Wheels Passport

Metropolis Post

Tai Audio

Ritter Battery

Glidecam

Media Blackout - Custom Cables and AKS

Wooden Camera

The Slider

Gamma Ray Digital Inc

rebotnix Technologies

Aerial Filmworks

CineTape

Willys Widgets

Broadcast Solutions Inc

Abel Cine

Visual Products

Technodolly

FJS International, LLC