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Light Ratio constant throughout a film?


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#1 David Calson

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Posted 15 April 2009 - 12:20 AM

If I stick to 5/1 for a part of it, is it common practice to do that the whole film? Thanks
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#2 Tom Jensen

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Posted 15 April 2009 - 12:28 AM

If I stick to 5/1 for a part of it, is it common practice to do that the whole film? Thanks

If that's what you want but it depends on the scene you are shooting and what you are trying to accomplish. It sounds a little contrasty to me. There is no set formula. The best thing you can do is shoot some light ratio tests. Start with 1:1 and go to 5:1 and see what happens.
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#3 David Mullen ASC

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Posted 15 April 2009 - 01:26 AM

If that's what you want but it depends on the scene you are shooting and what you are trying to accomplish. It sounds a little contrasty to me. There is no set formula. The best thing you can do is shoot some light ratio tests. Start with 1:1 and go to 5:1 and see what happens.


5:1 isn't contrasty but I'm not sure what it is...

2:1 is when the fill is 1-stop under the key (very flat), 4:1 is when the fill is 2-stops under the key (fairly common and conservative), and 8:1 is when the fill is 3-stops under the key (dramatic contrast but still with some shadow detail.) So I'm not sure where 5:1 falls in there but it's not that contrasty since the shadows would just be slightly more than 2-stops under the key.

Truth is that I personally find lighting ratios confusing -- they make more sense if you are lighting by measuring footcandles where the proportion of key to fill levels clearly means something. But converting it into stops is a waste of time and most people light in stops these days, not footcandles, so it makes more sense to talk about how many stops under the fill is compared to the key rather than a ratio.

You should test to discover what different fill levels do for the image, but the truth is that it doesn't make sense to fill everything to the same ratio when in real life, we encounter all sorts of different levels of fill, plus one would also take into account the mood of the scene and how frontal the key is. A 3/4 frontal key that is very soft may not need any fill at all and yet not look contrasty.
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#4 Tom Jensen

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Posted 15 April 2009 - 11:25 AM

I had a momentary lapse of brain function. 5:1 would be 2 and a half stops which is NOT contrasty. I started thinking in stops. 5 stops under key was what I meant to say would be very contrasty. What I also meant to say was shoot some tests and start with a 1:1 ratio and decrease the fill by one stop until you get to 5 stops under. Listen to David, don't listen to me unless you understand my jibberish.
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#5 David Calson

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Posted 15 April 2009 - 05:08 PM

No prob Tom, thanks for both of your advice, now to buy a light meter and start experimenting!
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#6 Tom Jensen

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Posted 15 April 2009 - 05:12 PM

No prob Tom, thanks for both of your advice, now to buy a light meter and start experimenting!


There is also a lab called RGB in Hollywood. It's either on Highland or LaBrea. You can buy movie film loaded in cartridges and they will print slides. This is the cheapest way to see what film will do.
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