How to make background paper brightness match face brightness? (example)

[mood_lover]

<p>I understand this can be done in post-editing but I'm trying to figure out how to get as close as possible to this effect in-camera with a light meter using the simplest setup possible: http://i.imgur.com/6PTJSgV.jpg</p>

[dhbebb]

<p>This is the kind of thing which is relatively easy to do the traditional way, in-camera, but very hard to do in post-editing. When digital imaging first came out, people were telling each other you could correct even the grossest errors with post-editing - they were WRONG!<br /> The tool of choice for balancing up lights is an incident light meter. If you do not have one, you can create a reasonable approximation by taking exposure readings with a styrofoam cup over the camera lens, pointing this at the normal camera position. Alternatively you can take readings off a card - to get readings which translate directly into exposure settings, the card needs to be gray and have 18% reflectance - for COMPARATIVE readings, a white card can be used. Simply move your lights backward and forward until you have the same reading at the background and your subject's face. Note that to get a "clean" white background but with tone showing (not blown out) you need to have the background lit one stop brighter than the subject.</p>

[fotis_tirokomos]

<p>The anwer to your question is reflective (preferebly spot) metering.<br>

Here is an example:<br>

Let us assume black and white for easyness, to speak about tones of grey representing brightness.<br>

It is crucial that you light your subject indepentently from your background (use two lights -- we also assume that you light your subject, as well as your background evenly).<br>

You measure the face with your reflective (spot) meter. Then you measure also the background with your reflective (spot) meter and you adjust the background light in order to get the same meter reading as previously.<br>

Subsequently, you open your aperture in the camera by 1-1/2 to 2 stops (choice is subjective) from your meter reading, to get a lighter grey tone (lighter from mid-grey) for face and backgound in camera. No matter how light or how dark this tone will be, it will always be the same for face and background.</p>

[fotis_tirokomos]

<p>Remember that the key is to use two separate lights, one to light your subject's face and a separate, indepentent, to light the background.</p>