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exposure compensation problem


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#1 Leigh Goldstein

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Posted 31 October 2007 - 03:03 AM

I am filming a situation with a few small, very bright white objects on a dark background.

I assume the camera (1014 XL-S) light meter will read a very low light and open the aperture very wide, but I don't need to see any detail in the dark background; I want to see detail in the highlights only (the bright objects).

Is there some way to estimate how far to stop down the aperture from the AE setting without exposing a roll of film?

Also, it is possible the AE setting will just read in the red (less than f/1.4). I can't really use a light meter here (I am shooting through a microscope). I guess in that case I am stuck with test exposures?

thanks,
Leigh
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#2 Mitch Perkins

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Posted 31 October 2007 - 02:08 PM

I am filming a situation with a few small, very bright white objects on a dark background.

I assume the camera (1014 XL-S) light meter will read a very low light and open the aperture very wide, but I don't need to see any detail in the dark background; I want to see detail in the highlights only (the bright objects).

Is there some way to estimate how far to stop down the aperture from the AE setting without exposing a roll of film?

Also, it is possible the AE setting will just read in the red (less than f/1.4). I can't really use a light meter here (I am shooting through a microscope). I guess in that case I am stuck with test exposures?

thanks,
Leigh


Since you're shooting through a microscope, (very cool by the way), I assume the project is not narrative? ~:?)

Can you bracket in 1/2stop increments? Kinda the same as testing, except that one of the exposures will be the one you want, and you'll have the shot...depending on how long the shot is...

Anyhoo autoexp. is right out. Or wait; what about filling the frame with the same value of white as the objects, and taking a reading from that?

Are you doing science? Science rules! ~:?)

Mitch
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#3 Leigh Goldstein

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Posted 01 November 2007 - 03:14 AM

Are you doing science? Science rules! ~:?)


--------
Science does indeed rule.

I am doing a documentary on micro-organisms, focusing on their visual beauty. It's technically challenging to do in super 8mm, easy to do in digital with special camera scopes.
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#4 Leigh Goldstein

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Posted 01 November 2007 - 03:21 AM

How about this? I put a white sheet of paper under the scope under the same illumination, and adjust the light down (or use darker paper) until the brightness seems equal to the subjects, then meter on that.... to get an idea anyway.
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#5 Alessandro Machi

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Posted 01 November 2007 - 11:57 AM

How about this? I put a white sheet of paper under the scope under the same illumination, and adjust the light down (or use darker paper) until the brightness seems equal to the subjects, then meter on that.... to get an idea anyway.


If depth of field is not an issue, you could always ND your camera, then even if the camera completely opens up aperture wise the ND will help keep the exposure where you need it to be. Vision 200T stock will give you the most latitude.

The white paper might be a good idea. You might also want to try manilla paper since straight white might fool your meter a bit too much towards underexposure. Or you could dive into the microscope and take an incident readiing (I saw that on Fantastic Voyage).
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#6 Rick Palidwor

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Posted 01 November 2007 - 01:17 PM

Can you put a 18% grey card in there and meter off that?
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#7 Leigh Goldstein

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Posted 01 November 2007 - 05:30 PM

That sounds best of all. I'll use that as a starting point and then do some bracketing on the actual subjects to see what works best.

Thanks for all your suggestions.

-Leigh
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#8 Rick Palidwor

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Posted 01 November 2007 - 11:09 PM

That sounds best of all. I'll use that as a starting point and then do some bracketing on the actual subjects to see what works best.

Thanks for all your suggestions.

-Leigh


The grey card is always best as the 18% reference is that the light meter uses to make recommendations. If you follow the reading it will show you how to make grey grey. Black and white fall into place around this.

Worth bracketing if you can afford it. I'd say a half-stop or less in either direction would do it.

Rick
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#9 Alessandro Machi

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Posted 09 November 2007 - 10:28 AM

I am filming a situation with a few small, very bright white objects on a dark background.

thanks,
Leigh


Based on the above quote, I think manilla would give a more accurate exposure than a grey card.
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Gamma Ray Digital Inc

Visual Products

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Aerial Filmworks

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Wooden Camera

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