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Lighting Ratios/Meters/Contrast


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#1 David Calson

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Posted 28 November 2008 - 05:30 PM

Here's me trying to understand light meters,

Lets say I'm lighting a shot, I want the center character the brightest with the people on the sides to be less lit. My meter says I need to put my main person at 5.6, (okay, I set the lens to 5.6) now lets say that I want the other non-important people to be two stop under, I should make the light meter says they are at_____? Maybe an f/2?

Lighting ratios, what ratios do you like work at for normal, not high-key,not low-key situations, 2:1, 3:1?
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#2 Rob Vogt

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Posted 28 November 2008 - 06:18 PM

Hey Blade,

In order to do this kind of setup have your lens' aperture set for the same F Stop as the person in the center (5.6). You are going to have to change the lights for the people around him with flags, dimmers ect. to get a 2.8. As for the light ratios it depends on the film stock. For Kodak vision 3 they recommend 2:1 or 3:1.

http://motion.kodak....5219.htm#expind

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#3 Rob Vogt

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Posted 28 November 2008 - 06:26 PM

Sorry for the double post but it's not letting me edit mine for some reason.

Here's an example of the exposure data for Vision 2 500T
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#4 David Calson

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Posted 28 November 2008 - 06:39 PM

Thanks for the reply Rob, so to get my other talent two stops under I would need to position/dim the lights until they read 2.8?
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#5 David Calson

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Posted 28 November 2008 - 07:51 PM

Also, here's another question,

Let's say that you want to set the key at f/1.4, how would you know how low to set the other lights, I mean, wouldn't the meter have to show something brighter than 1.4 for you to know, do meters go past 1.4?
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#6 Igor Trajkovski

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Posted 28 November 2008 - 09:20 PM

You can switch your meter to measure EV units.

For example:
With film rated at 320 ASA,
at 25 fps and 180 degree shutter
and EV 5 you will get f/1.4

The EV value will be shown with digits and
on the analog scale a pointer will show you the F number.

Go to your area where your light level should be 2 stops under and
adjust the light source till you read EV 3.


OR...


Simply use the difference function if your meter has one.

Make your main reading, switch to difference mode,
and as you hold again you metering button and walk
around measuring it will show you the difference in F stops
from your first reading.

For details consult your meter manual.


On analog meters with footcandles scale,
the numbers are one stop appart with
1/3 or 1/2 stop division inbetween.

You mentaly mark your FC (or EV)
or set your memo pointer (if any) at your
main area and use it as reference to
measure your darker area,
to see when your needle comes at 2 stop under....

Here an Sekonic Studio Master analog scale:

Posted Image


Say your needle shows 40 fc.
At 50 ASA film with 24fps and 180 shutter
aperture is around f/1.2

Set your memo pointer at 40fc (the red triangular thing, here at ~5fc).

Go to you area where you want 2 stops under and
adjust lights till your needle comes at 10fc.

Thats it.



Hope this helps.


Regards

Igor


PS: BTW, the sample meter scale is a selfmade animated GIF
that i use as signature at another forum.... :)
Too sleepy to find a picture with a still needle....
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#7 David Mullen ASC

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Posted 28 November 2008 - 10:13 PM

You can also set your meter to a higher ASA value if you want to read objects that get too low in f-stops, as long as you remember that you deliberately mis-set the meter -- i.e. you switch your meter to 2000 ASA instead of 500 ASA, and now your f/1.4 key reads f/2.8 and the shadow that is three-stops under reads f/1.0. Just don't forget that you have the wrong ASA value input.

Yes, when you want other parts of the frame to be darker than the subject, you have to get the light level on those areas to be lower, either by flagging or scrimming or netting the light, or using a lower-level unit for the darker areas, etc.
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