Product Photography Using a Digital Box

[Sonny]

We've all seen how to build a DIY light box, but tutorial addresses some of the difficulties when shooting small product photographs; things like controlling highlights and shadows.

http://www.layersmagazine.com/produc...itial-box.html

[andyz]

I'm used to seeing a gray card used for white balance. He indicates it is used for exposure when a light meter isn't available. Is this because the digital camera wants to take everything to neutral gray?

[kenw]

a grey card is more typically used for exposure, but can also be used for white balance. As long as it is color neutral, you can use any shade of grey or even (!) white.

The only advantage of using a 18% grey card for WB is that you probably already have one for exposure.

[Jeff Lane]

I'm used to seeing a gray card used for white balance. He indicates it is used for exposure when a light meter isn't available. Is this because the digital camera wants to take everything to neutral gray?

Pretty much, Andy. The average stuff you see in normal life is about half dark and half light, and if it's not, your iris tries to compensate until it just about is. The camera's engineers designed it to try to do the same thing, by assuming that "half light half dark" is almost universally true, in order to make an in-camera meter that would work for most situations. (This works out to 18% gray for some I reason I dont' understand. Brad Barton, in his excellent beginning class, wasn't able to dumb down the math enough for me to ever get it, but I trust him because it works.)

However, if you have an all-black wall or an all-white wall with a little subject in the middle of it, the camera's meter wants to "assume" that all the light coming to the sensor should be about 18% gray, so it compensates by calculating exposure up or down until it "sees" the whole scene as 18% gray, resulting in an over- or under-exposure in the subject you're really interested in. (Example - photograph a snowy scene relying on the in-camera meter and you'll see all the snow turn gray.) You can overcome the camera's bias toward 18% gray by setting it on manual, putting an 18% gray card where the subject will be, and metering with just that card in your camera's frame, then removing the card and shooting the whole scene on those manual settings, while your camera screams at your that you're just wrong. (Am I the only one hearing those voices?) Your subject will be exposed correctly, and the background will have its appropriate light value, as well.

(See, Brad, I really was taking notes.)