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Day for Night


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#1 Dave Plake

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Posted 30 July 2005 - 12:27 AM

What are anyone's thoughts on putting two linear or one linear and one round pola in a matte box and rotating them against eachother for day for night?
shoot on a bright sunny day with tungsten film to increase blue.
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#2 Manu Anand

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Posted 30 July 2005 - 01:24 AM

Hi Dave,
Im not sure what using two polarizers will achieve since..... two polarizers will cancel each other out at an angle of 90 degrees to each other letting very little light pass through.
So lets see ...the polarizer in front of the lens lets polarized light through but the one behind it then basically as you rotate it away from 90 degrees allows some light to pass through....Its acting more like a variable ND filter cutting light(allowing less or more light to pas through as you rotate it).

So im not sure what you intend to achieve..with two polarizers for day for night??
Here are some interesting links on polarized light and polarization

http://www.glenbrook...ght/u12l1e.html

with examples :To cut glare off the road buy polarised sun glasses with their polarization axis perpendicular to the road.

This one is fascinating reading about
Polarization Compasses.... how auroras are polarized.....bees and polarization...the vikings and polarization.....Display sytems and polarization ( like LCD screens have a polarisation filter)
So lots of interesting stuff on Polarized Light .........

http://www.polarizat...-net/index.html

Manu Anand
Bombay
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#3 Dave Plake

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Posted 30 July 2005 - 08:12 PM

so no one's ever tried it huh? Rotating two polas against one another to darken a scene to look day for night?
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#4 David Mullen ASC

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Posted 30 July 2005 - 08:29 PM

so no one's ever tried it huh?  Rotating two polas against one another to darken a scene to look day for night?

<{POST_SNAPBACK}>


Why would that be very different than using one pola and underexposing on top of that?
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#5 Stephen Williams

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Posted 31 July 2005 - 05:25 AM

Rotating two polas against one another to darken a scene?

<{POST_SNAPBACK}>



Hi,

I used to do that shooting Slit Scan many years ago! to fade out part of the image! Slit Scan was the effect Doug Troumble (spelling) used on 2001!

Stephen Williams DP

www.stephenw.com
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#6 Sam Wells

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Posted 31 July 2005 - 04:39 PM

Sort of acting as a pola plus a variable ND; or a pola and a variable grad except the graduation is not linear but angular (w/ respect to what's polarised in the scene, if anything is).

I think it's an interesting idea but as an all in one solution it's rather contingent on what you're shooting...

-Sam
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#7 Sam Wells

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Posted 31 July 2005 - 04:43 PM

....Its acting more like a variable ND filter cutting light

<{POST_SNAPBACK}>


Oh you already said that, sorry to repeat it.

-Dept of Redundancy Dept.
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#8 Dave Plake

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Posted 31 July 2005 - 06:35 PM

Mr. Mullen I was told that when you adjust your polas, you are adjusting them in relationship to one another and absorbing all the scattered light - allowing only those rays that are perpendicular to your lens to pass.

If you use one pola which blocks some of the polarized light, then underexpose, your are also underexposing your highlights, effectively reducing your contrast range within the image. If you use both a linear and cirlcular pola and do not underexpose your highlights, but let your shadows go black, your are increasing your contrast and yielding a more extreme result.

I guess you have not tried this.
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#9 Remi Adefarasin

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Posted 06 August 2005 - 12:12 PM

Dave,

I've tried it by eye but it doesn't make day look like night. There are a lot of things you need to do with day for night photography. Keeping the sky out, keeping scene backlit by the sun, putting massive sources in windows to simulate failing light etc.

What worries me most though is calculating the exposure. A polar is 1 2/3 stops okay. Two is 3 1/3 in theory but that depends on the rotation. You can achieve almost no light transmission.
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#10 Charles Haine

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Posted 06 August 2005 - 03:20 PM

Chris Chomyn, on SEA OF DREAMS (previous title BRIDE OF THE SEA) shot some day for night facing the ocean in the middle of the day using a double pola effect, I think on a daylight film with a blue and mabye a green filter.

When he talked about it, I think he mentioned something about wanting to get rid of hard reflections on the water by using the Polas, since hard reflections on waves would clearly show the sun, and be very hard to paint out digitally. The sky was in shot (but not the sun), and digital stars were added in Post.

I don't think the film has been released yet.

chuck haine
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