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Lighting by EYE


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#1 Rob Wilton

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Posted 02 December 2006 - 01:08 PM

Dear all,

Im shooting next week mostly with HMI lights. Its almost a 1st for me, because Im used to shooting with Tungsten lights in the studio.

My queston is maybe too personal, or not at all. How would you light by eye if youre using HMI's next to 2900K practicals, and youre used to using tungsten lighting as a standard.

Does the eye adapt to the standardized colour temp (5600K) and the practical would automatically look a lot hotter (colour temp wise) whilst next to HMI lights?

Does this also apply if you use coloured gels?

thanks!

Rob
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#2 Jonathan Bowerbank

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Posted 02 December 2006 - 03:21 PM

The difference in color temperature is VERY noticeable. If you've worked with mainly tungsten lights, and have at least used a full CTB gel on one of your sources and noticed the difference, then you shouldn't have a problem discerning between the HMI & Tungsten lights.

Everybody's eyes are different, you may either see the HMI as white light and the tungsten as a yellow/orange, or maybe you see the tungsten as white and the HMI as blue. Either way, you'll see the difference, allowing you to light by eye.

:)
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#3 Rob Wilton

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Posted 02 December 2006 - 03:31 PM

Dear Jonathan,

I think you misunderstood my question. I meant to compare standard interior practicals (around 2900K) to HMI (5600K).

If after a couple of minutes on set ur eye adapts, and u start seeing your HMI lighting as white, then hypothetically the practicals would start looking quite red? Or not?

Does this reasoning apply to coloured gels as well, in comparison?


thank you!


Rob Wilton
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#4 Jonathan Bowerbank

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Posted 02 December 2006 - 03:50 PM

I think my answer still applies. Don't think 2900k is quite "red", but your eye compensates and balances for all lights seen, so I can't say what YOU will see. Your practicals will most likely look a lot more yellow than your tungsten lights, your tungsten lights will look more yellow than your HMI, and your HMI will look a lot more blue than the other two sources.

However, how it registers onto film will be dramatically different. But still, 2900k isn't a dramatic color shift, relatively. It'll just be a bit more yellow than your normal tungsten sources.
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#5 Michael Nash

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Posted 02 December 2006 - 05:27 PM

If after a couple of minutes on set ur eye adapts, and u start seeing your HMI lighting as white, then hypothetically the practicals would start looking quite red? Or not?

Does this reasoning apply to coloured gels as well, in comparison?
thank you!
Rob Wilton


Stand in your house on a sunny day with the curtains open, and the lights off. Let your eyes adjust to the natural color. Then turn on some lights in the house. Do they look orange? Yes. They'll look even more orange on film, but you can still see a difference in color by eye.

Outdoors in daylight 5600K appears white to our eyes. Indoors at night 3200 appears white to our eyes. That right there illustrates how our eyes/brains adapt to the predominant color of light. This principle applies to colored gels as well, although I've found it takes much longer exposure to saturated colors for them to go "white" by eye. But when you step away from a strong color after awhile, even if you can still perceive the color (it hasn't gone white to your eye), everything else will have appear to be tinted toward the complementary (opposite) color.

Have you ever noticed after sunbathing by the pool or on a beach with your eyes closed, everything looks bluish when you open your eyes after awhile? It's because you've been staring at the warmer colored light coming through your eyelids.

Try this link: http://www.ebaumswor...r-illusion.html
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#6 Jonathan Bowerbank

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Posted 02 December 2006 - 05:49 PM

That video clip's a trip
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#7 David Mullen ASC

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Posted 02 December 2006 - 06:43 PM

Your eyes can see the difference, just not as extreme as film will render the difference. Only thing is, with film and your eyes, a very bright light will look less saturated, so an uncorrected HMI on tungsten stock or an uncorrected tungsten on daylight stock will look different depending on how overexposed it is (however, the ambience created from the bounce will still have that color). An HMI spotlight on tungsten stock will look very blue if two-stops underexposed for moonlight but somewhat cold and washed-out when three stops overexposed.
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#8 Frank Barrera

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Posted 02 December 2006 - 07:44 PM

Can someone explain why the optical illusion at the above link works?

very interesting...

f
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#9 Michael Nash

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Posted 03 December 2006 - 01:54 AM

Can someone explain why the optical illusion at the above link works?

very interesting...

f


I don't think I could explain the physiology of it, but it's called "chromatic adaptation." Think of it as though your eye/brain has an auto white-balance, that always attempts to see things as the "correct" color. Just like a video camera, when white balanced to a particular color, a neutral (gray) will appear shifted toward the complement.
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#10 Rob Wilton

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Posted 03 December 2006 - 02:07 PM

Thanks everybody! I start shooting next Saturday,
I'll try to keep my eyes open and try not to visualise that clip too much :)

Rob
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#11 Jim Feldspar

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Posted 03 December 2006 - 02:13 PM

I don't think I could explain the physiology of it, but it's called "chromatic adaptation." Think of it as though your eye/brain has an auto white-balance, that always attempts to see things as the "correct" color. Just like a video camera, when white balanced to a particular color, a neutral (gray) will appear shifted toward the complement.



No, I think it's just a gag. When the clip is done, if you put the play cursor near the end of the timeline,
you get a black screen that says "replay video" and "send to a friend". It won't let your fresh eyes see
the end of the clip.

So, hit replay and as soon as the image comes up, instantly click to near the end of the clip. You'll see the
different colored image but having only glancingly seen the black dot for a second, you know that your
eyes aren't doing some funky adjustment. The different images are edited into the clip.

Edited by Jim Feldspar, 03 December 2006 - 02:14 PM.

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#12 Hal Smith

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Posted 03 December 2006 - 03:00 PM

At the Broadway Lighting Master Classes a couple of years ago Beverly Emmons (a well regarded Broadway lighting designer) did a real-time demonstration of the eye's ability to color balance just about anything to white. She lit a dress dummy with a white linen costume first from one side with a magenta gelled light at a fairly low level. Then she added another light from the other side, same gel but slightly brighter. She went back and forth from side to side brightning the light in steps. By the time she had the dummy lit at somewhere around 200FC the dummy looked like it was in white light. Then Beverly pulled her rabbit out of the hat - she added a fairly bright white light (ungelled) from the front of the auditorium.

The result?

The white light appeared to be colored bright green. Beverly had "coaxed" the audience's eye into believing magenta was white - by comparison making the green in white light very predominant. Beverly's lecture was to demonstrate why sometimes in lighting design you try something that just plain doesn't work. The relevance to film is you really can't trust what your eye is telling you unless you have a good reference light of known color temperature to compare it to. I personally use a 3200k tungsten reference when in doubt.
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#13 Felipe Perez-Burchard

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Posted 03 December 2006 - 03:04 PM

No, I think it's just a gag. When the clip is done, if you put the play cursor near the end of the timeline,
you get a black screen that says "replay video" and "send to a friend". It won't let your fresh eyes see
the end of the clip.

So, hit replay and as soon as the image comes up, instantly click to near the end of the clip. You'll see the
different colored image but having only glancingly seen the black dot for a second, you know that your
eyes aren't doing some funky adjustment. The different images are edited into the clip.


I'm not sure this is the case... When the "cut" happens it goes directly to the b&w image.
This is the principle of an after-image which explains why the "colored" photo lasts as long as you keep staring before you glance away.
http://en.wikipedia....wiki/Afterimage

Hope it helps,
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#14 Riku Naskali

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Posted 03 December 2006 - 04:23 PM

It's interesting that everyone says your eyes adapt to color... I see 2900-3200K always as yellow no matter how long I've been staring at it. And generally 5500K as "white". I guess it's entirely personal how one perceives the differences.
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#15 Jim Feldspar

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Posted 03 December 2006 - 11:30 PM

I'm not sure this is the case... When the "cut" happens it goes directly to the b&w image.
This is the principle of an after-image which explains why the "colored" photo lasts as long as you keep staring before you glance away.
http://en.wikipedia....wiki/Afterimage

Hope it helps,


Thanks, that's a good article with an interesting demo. built into it and I enjoyed reading it...but if you play
the clip from the start and as soon as you see the image you click to near the end of the timeline, you'll see
the different image. If you take say a second or even two to react, I think that is not long enough to cause
this phenomenon.
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#16 Matt Sandstrom

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Posted 04 December 2006 - 10:09 AM

It's interesting that everyone says your eyes adapt to color... I see 2900-3200K always as yellow no matter how long I've been staring at it. And generally 5500K as "white".

to me it's all about intensity, absolute and relative. today was dark, rainy and overcast here so i had all the lights on in my apartment, and the outside looked very blue and the tungsten lights very warm. i assume that's because they were both low intensity. sunlight always looked white to me, as did 1000w halogens. when my brain is in doubt though i think it handles it the way you say. ;-)

/matt
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