Using a Grey Card for Better Exposures

by | Mar 20, 2019

Today’s Post by Joe Farace

Continuing Monday’s theme of obtaining proper exposure, presented for your approval…

I strongly believe that in photography there are no one perfect or correct way to accomplish anything, although some platform/trade show presenters may disagree with me arguing that only their way is the one, true perfect road.

There is no “my way or the highway” in photography. In my world and on this blog you get to choose the methodology that works for you. Even a road less traveled is OK, if it produces the results that you want. If it doesn’t, it’s time to look at some alternatives and with a little bit of testing, fine-tune your methods to your preferred subject matter and personalized way of working.

Part of what makes the Tokyo Motor Show lots of fun to attend is the interesting and unusual concept cars that automobile companies, such as Nissan, put on display. While it’s unlikely that the company would even build such a beautifully retro roadster as this one, I like to think of it as the spiritual successor to the Datsun 2000.

How I Made this shot: Sometime when I have to work quickly shooting in locations that have complex and mixed lighting, like the Makuhari Messe Convention Center, I’ll use Program mode (not Green mode) as in the above photograph of a Nissan concept car at the Tokyo Motor Show. The image was shot with a Canon EOS Digital Rebel and an EF 18-55mm kit lens with an exposure of  1/60 sec at f/5 and ISO 400 with the tiny pop-up flash adding a bit of fill.

Back to basics: If you get a handheld meter or in-camera setting of 1/500 sec at f/11 and want to use a slower shutter speed to allow for subject or camera motion and choose 1/125 sec, you’ll have to adjust the aperture so the same amount of light falls on the sensor. By selecting aperture (Av) or shutter priority (Tv) mode, your camera will do this calculation for you, eliminating any guesswork. And then there’s the substitution method.

Using a Gray Card: When using the substitution method, you visually replace an object within the scene with an object of known reflectance, such as a Kodak Gray Card or Gray Card Plus and take a reflected-light reading off of that object. You can also substitute objects that match the light reflectance of an object in the scene. Don’t have a gray card? Back in the film days I used to take a reading off grass, if there was any in the scene, and then open up one stop.

When pointed at subjects with reflectivity near 18%, reflected light meters are calibrated to provide an accurate exposure. Yet, the exact value varies and details are complex with some handheld meters measuring 12% with others at 14%. By placing a Gray Card in the scene to be photographed and taking a reading off of it with any reflected light meter, you should expect consistent exposures but sure be sure to read the fine print instead of just accepting the reading as gospel. The instructions packed with the Kodak grey card, for example,  contain the following advice about adjusting meter readings:

  • Normal subjects: “Increase the indicated exposure by ½ stop.”
  • Light subjects: “for very light subjects decrease exposure by 1/ stop”
  • Dark subjects: “If the subjects is dark or very dark increase the indicated exposure by one to one and one-half stops.”

Ilight.bookf you enjoyed today’s blog post and would like to treat Joe to a cup of Earl Grey tea ($2.50), click here.

Along with photographer Barry Staver, Joe is co-author of Better Available Light Digital Photograph that’s now out-of-print but new copies are available from Amazon for $21.88 with used copies selling for four bucks. For some reason, the Kindle price is really high.