Equipment, Musings, Photography, Techniques

More Grey News

What’s the point of using a grey card? We’ve all heard the reasons, better white balancing under specific lighting conditions, but mostly for establishing the correct exposure value for any mid-tones evident in a proposed subject capture. Whatever that means?!?

In essence it’s all about exposure, and deciding the right exposure for a particular situation under the prevailing lighting conditions, be they natural, artificial or a mixture, and being able to reproduce that tonal range using whatever display medium you choose to use. It’s also about colour rendition, but more on that later, maybe.

Now, the first thing to realize is that all this has its grounding and basis in film, specifically black and white film, and in rendering good tonal range and contrast, on a piece of photographic paper. As such, as photographers got more and more into the quality control of their final dark room output, they started to focus on other elements in the workflow, such as chemical strength and age, negative density, and ensuring the best possible negative exposure so as to maximize the image information available to them when it came time to make prints.

Now I remember as a lad, in the dark room, making contact prints and test strips. The contact prints (thumbnails) allowed me to quickly choose which negative I wanted to work with. From there a test strip was made in order to determine the correct exposure of the enlarged negative on the paper being used.  This exposure ruler enabled me to look at my images and make better decisions about how best to print a particular negative.

Photographers like Fred Archer and Ansel Adams took this exposure rule and then applied it to image capture thus developing what is now referred to as the Zone System, (and it seems that the rest of us photographers have been held to ransom over Grey Cards because of it, ever since).

With this methodology and approach to image capture, a scene was evaluated for the range of tones evident. Then the photographer would make a value judgement based on which part of the scene should be put in which zone, what information was important, and what information could be discarded, as not all that information could be captured by the negative, and even more importantly, even less of that information could be presented in the final print.

In order to make exposure easier for photographers, so that they didn’t have to DIY Grey Cards, Adams started advocating Kodak’s 18% Grey Card, as it was the closest match to Middle Grey in Adam’s & Archer’s Zone System. Now this advocacy was so that a photographer could measure the exposure for an average tone, and then look at the scene and adjust camera exposure accordingly. It wasn’t the be all and end of the process, but simply a tool to establish a starting point.

I never actually got that far into it all, to visualize a scene beforehand as to how it might look in print, and to use a standard reference card for measuring exposure, so I never made connection between a zone ruler to my darkroom development exposure ruler. However, in this digital age, I have been forced to re-confront this age old photographic bastion and come to my own terms with it, which I’m finding reasonably comfortable.

The guiding principle rule here with digital photography and using a grey card, I guess, is wysiwyg, and anything that helps to minimize capture errors prior to post-production is worth consideration. But let’s just do a step back for a moment by asking a few questions.

  • How with the final image be presented to the audience? (Screen, Print, Projection?)
  • What is the dynamic range or latitude of that display media?
  • Are the output colours in the same colour space and gamut as your post-production tools? (Computer Display, Operating System, Graphics management, Software?)
  • Has your post-production system been calibrated?
  • What colour management does your digital camera use?
  • Have you calibrated your camera with the rest of your image development and processing system?
  • What is the dynamic range or latitude of your camera’s sensor? (Does this change depending on the lenses you use?)

An understanding of how your system works, how it captures colour & contrast and subsequently treats them and represents them in final presentation is crucial to visualizing how the scene you stand before will appear ‘On Display,’ so to speak.

From there, controlling White Balance at time of capture, influences colour rendition. Determining mid-tone exposure dictates the tonal range that is recorded. Playing with these two factors at various times of day will change the vibrancy, saturation and tonal contrast in your images.

Anyone who has taken a photo on a dull day and got grey, washed out, muted colours will know the disappointment that such images bring, and that because, they’ve made basic exposure compensation errors by not choosing where they want the details to appear on a “Zone Ruler” range. In end effect, all this, “Grey News,” is about, “Think first, Shoot later.”

For today, that’s what’s in my

Line of Sight.

Addendum [2011.12.08]

Do you love it or hate it when watching or reading something long after reviewing a topic, “the penny drops” and you get that “ah ha!’ moment? Well today I was watching a series of vids from learnmyshot.com on youtube and during the White Balance vid it hit me smack in the face. Just a simple image of a custom WB done with a white card. Why did it look grey? Then Dean Collins joined the chorus of voices in the back of my head.

Of course! “The exposure meter of the camera tries to make everything 18% grey,” so white turns grey, and black also turns grey… How many times have you gone over that statement and said, yeah I get that… but in truth don’t? This is the reason why making a custom WB setting with either a white card or an 18% Grey Card works the same. Plus, these better render colour temperature than using a black card, as the black card tends to absorb everything. “Ah Ha!, I get it!”

Now, back to gazing at the floor…

More Grey