Jump to content


Photo

Double Polarizers


  • Please log in to reply
6 replies to this topic

#1 Stanley Kubrick

Stanley Kubrick

    New

  • Basic Members
  • Pip
  • 2 posts
  • Cinematographer

Posted 11 March 2010 - 11:45 AM

I'm going to be shooting a 16mm film for school in the next couple of weeks and I just wanted to know the effects certain filters would have (we're shooting Kodak Vision 2 500T; on the ArriSR1 if that helps at all).

We want to set up the camera right in front (outside) of a clear restaurant door and shoot 2 of our characters eating inside. The problem is that if we do that, there will be a reflection of the camera in the shot. We can't shoot the scene at night and we have to shoot the scene straight on.

I know polarizer filters will eliminate the reflection on the glass, however, I'm worried there will still be a noticeable reflection. My question is this: if we used 2 polarizer filters, would it help reduce the reflection further? Or are there diminishing returns?

*Because of the daylight mixed with the stock's speed, we can afford the loss of the 4 stops the polarizers will create.

Thanks in advance for your help.
  • 0

#2 Saul Rodgar

Saul Rodgar
  • Basic Members
  • PipPipPipPip
  • 1682 posts
  • Cinematographer

Posted 11 March 2010 - 12:12 PM

So you mean to tell me that despite rising from the dead, you, Stanley Kubrick (a highly experienced professional and award winning still photographer before becoming a film director) you don't know the answer to this question? :lol: Please change your alias to your real name as per forum rules.

A double polarizer should only be used after extensive testing and as carefully as possible. Two polarizers in front of the lens, depending how they are positioned, could prevent most light from reaching the image plane, causing some serious underexposure. Try holding them in front of you and turning them slowly to see what I mean. Also you would need to add 4 stops to your interior restaurant exposure as compensation, making it very impractical all around

The easiest thing to achieve what you want is to keep the camera at off to the side so as to not see its reflection in the shot while using one polarizer only. If the camera must be at a right angle form the window, then cover the camera, tripod and operator in black duvetyne or camouflage cloth or whatever is needed to make it blend to the surroundings outside the window while only using one polarizer. If the camera is positioned somewhere inconspicuous in the frame and movement is kept to a minimum, you should be able to keep attention away from it.

Edited by Saul Rodgar, 11 March 2010 - 12:17 PM.

  • 0

#3 Stanley Kubrick

Stanley Kubrick

    New

  • Basic Members
  • Pip
  • 2 posts
  • Cinematographer

Posted 11 March 2010 - 02:23 PM

Oh I'm sorry. I'll change my name.

Thank you for the help. So what do you think about the reflection issue? Would a second polarizer diminish the reflection any further than a single one?
  • 0

#4 Gus Sacks

Gus Sacks
  • Sustaining Members
  • 287 posts
  • Cinematographer
  • Los Angeles, CA

Posted 11 March 2010 - 03:05 PM

If the shot isn't showing the whole window you could probably put a 12'x or 20'x solid behind camera so the reflection is just of the 'black' behind you.
  • 0

#5 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 11 March 2010 - 04:28 PM

Exactly what shot do you want? There is probably a better way to solve the problem than stacking 2 POLAs, which do tend to have severely diminishing results as compared to just one POLA.
  • 0

#6 Dominic Case

Dominic Case
  • Basic Members
  • PipPipPipPip
  • 1357 posts
  • Other
  • Sydney Australia

Posted 11 March 2010 - 04:33 PM

Two polarisers probably won't do any more than one. If the reflected light is perfectly poalrised, one filter will do the job. If it isn't (as most likely the case), then adding more polarisers won't help at all.

Best (as suggested before) try to minimise the light outside. A black tent or flat would be one way.

And can you throw more light on the characters inside the restaurant? That would help too, if you don't see too much of the exterior (except the glass) to give the trick away.
  • 0

#7 Rob Vogt

Rob Vogt
  • Basic Members
  • PipPipPipPip
  • 437 posts
  • Other
  • New York

Posted 11 March 2010 - 07:39 PM

Or you could try one of those polarizing gels
  • 0


Opal

Ritter Battery

Visual Products

Media Blackout - Custom Cables and AKS

CineLab

Paralinx LLC

Glidecam

Metropolis Post

Aerial Filmworks

The Slider

Gamma Ray Digital Inc

FJS International, LLC

Wooden Camera

Abel Cine

Rig Wheels Passport

Broadcast Solutions Inc

rebotnix Technologies

Tai Audio

Willys Widgets

CineTape

Technodolly

CineTape

Opal

rebotnix Technologies

Willys Widgets

Technodolly

The Slider

Visual Products

Tai Audio

Ritter Battery

Abel Cine

Rig Wheels Passport

Aerial Filmworks

Media Blackout - Custom Cables and AKS

Glidecam

Metropolis Post

Wooden Camera

FJS International, LLC

Gamma Ray Digital Inc

Paralinx LLC

CineLab

Broadcast Solutions Inc