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Gray Card question?


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#1 Tim Carroll

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Posted 24 May 2007 - 01:16 PM

Used to know this but now am fuzzy on it.

When taking a reading with an 18% gray card and artificial lighting, do you point the card directly at the light source and aim your spot meter at the card from the direction of the camera, or do you point the gray card directly at the camera and take your spot meter reading from the direction of the camera?

Thanks,
-Tim
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#2 Chris Keth

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Posted 24 May 2007 - 01:44 PM

Used to know this but now am fuzzy on it.

When taking a reading with an 18% gray card and artificial lighting, do you point the card directly at the light source and aim your spot meter at the card from the direction of the camera, or do you point the gray card directly at the camera and take your spot meter reading from the direction of the camera?

Thanks,
-Tim


To get approximately the effect of incident metering, you want to do your second option. The trick here is that, depending on the angle of the card to lights and the spotmeter, you can easily get a couple stops of variation in your readings with any given setup. No matter what you do here, all of these readings should be from camera, as close as practical to the lens axis.

Edited by Chris Keth, 24 May 2007 - 01:45 PM.

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#3 Nick Mulder

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Posted 24 May 2007 - 03:55 PM

I would have guessed have it on the same angle as the object in the frame that you want to be exposed correctly as...

So if you wanted a particular side of someones face exposed correctly find the tangential plane to an area in that part of the face and go from there...

The more you angle something away from the normal to the rays the less 'flux' of light it will receive (think about the extreme where the plane is on the same angle as the rays... i.e it would get zero light...)

I don't think there really needs to be any rules - but a clear understanding of how it all works will allow you to come up with your own system - a kind of "learn why the rules are there before you break them" thing ...

Having said that metering from the perspective of the camera is a pretty solid rule for the particular application.
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#4 Mike Williamson

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Posted 24 May 2007 - 09:36 PM

I always bring in a chart light and put it right next to the camera, then aim the card at the camera. The chart light should be neutral, whatever that is for the scene (for example a tungsten light for tungsten film).
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#5 Jonathan Bowerbank

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Posted 25 May 2007 - 04:48 AM

Be careful with the texture of gray card you're using as well. Those cheaper $6 photographic ones usually have a very glary surface which will obviously corrupt your spot reading.

The Kodak "Gray Card Plus" has a textured 18% gray that doesn't glare nearly as much, so just keep that in mind when taking your reading :)
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