"How do you know that?" Characteristics of light in photography

The depth of field (what's in focus) in this photo is pretty small.  About all you can read is the one line - "How do you know that?" 

I don't consider myself an expert photographer but I do enjoy sharing what I have learned, often the hard way, over the years.  Most things I've learned from experience and that's how I "know that." One of the best ways to share what I've learned is by example, which I try to do when blogging.

Being at home more has led me to experiment photographing things around the house.  In this case, an old non-fiction book and a pair of antique eyeglasses my dad gave to me.  They belonged to a relative but no one remembers who.  I'm not great at still life photography.  I do better at making photos of things that have been arranged for me, like wildflowers and mountains than things that I have to arrange.  However, we grow by working on things we are not good at.

The very first topic in my photography class is what I consider the most important.  It is not camera settings, the latest gear, or posing beautiful subjects.  I consider light the most important element in photography.  The right light can make a photo but even the most beautiful subjects can be poor photos in the wrong light.  Photographers love to talk about good light and bad light.  Light is not good or bad, but different kinds of light work better in different situations.

Light has three characteristics

1. Direction
2. Color
3. Hard (direct) or soft (diffused)

Color Under LED Lights

I want to show you a little example of hard vs. soft light using a couple examples of photos I made with the book sitting on our kitchen table.  Above the table is a hanging lamp with 5 LED bulbs.  To the right is a set of French Doors that lead out to a covered deck area.  Those two light sources have different characteristics.

The lens aperture and focal length in these two photos are the same. The LED lights made the paper very yellow when using the auto white balance setting.  I corrected the white balance (light color) in each photo to be as realistic as possible. 

Direct Overhead Light

Indirect Side Light

Notice the shadows in the first photo.  They come from the overhead lights.  In the second photo what shadows can be seen are faint and soft.  The overhead lights also made the tabletop brighter.  The indirect light from the right made the book in the background brighter.

Indirect Light

Direct Overhead Light

In the second example, you can see how the direction of the light creates different shadows.  The photo with the indirect light coming from the right created a shadow in the crease of the book.  The direct light also overpowered the indirect light and minimized the reflections from the door in the lens.  The indirect light highlighted the brass hinge and the color of the eyeglass arms.

“There are no rules for good photographs, there are only good photographs.”

–Ansel Adams

Neither photo is right or wrong, just different.  As the photographer, it is up to us to use the light in our composition to emphasize what we want and de-emphasize what we don't want.  

Before making your next photo think about the light.  Where is it coming from?  Is it creating hard shadows?  Is it warm and pleasing or blue and cold?  How can you use that light to make a better photo?

Fooling Your Camera's Auto White Balance

All light has color characteristics.  Our eyes and brain have been created to discern and adjust for most color differences, which we never notice.  However, the sensor and high powered computer in our digital cameras are not as smart as we are and can be fooled.

The color of light is expressed as a temperature in degrees Kelvin.  Sometimes it's warm, like the sunlight at sunrise.  Other times it's cool like the sunlight on a cloudy day.  Artificial light also has color.   Florescent  bulbs have a cool blue tint while tungsten incandescent bulbs have a warm yellow tint.

Your digital camera has a feature called Auto White Balance (AWB) that tries to measure and adjust for these differences in light color so things that appear white to your eye are white in your photo.   Modern cameras do an amazing job and get this right most of the time, however they can be fooled.

If a scene is dominated by one color the auto white balance function can be fooled into assuming that the light has a lot of that color in it. This can result in an incorrect white balance and an undesirable color cast in your photo. The two photos below show one case where the camera was fooled.

Auto White Balance

Daylight White Balance

About 3/4 of this photo is dominated by a strong yellow color from the field of Canola (Rapeseed).   In auto white balance mode the camera senses all this yellow and thinks the color temperature of the light is warmer than it really is.   The camera makes an automatic adjustment (the auto port of AWB) to make the photo cooler.  As a result, the photographer's skin has a sickly blue color.

In fact, the photo was taken on a bright sunny day around mid-day and the light was cooler (bluer) than the camera thought.  In the second photo I changed the white balance from auto to Daylight.  If you compare the two photos you can see that the photographer's skin tone in the second photo is much more natural.

So, when do you rely on Auto White Balance and when do you go to manual white balance?  Here's what I do.  Most of the time I don't care about the white balance setting on my camera because I almost always take my photos in RAW format rather than JPEG.  JPEG format has the camera's color adjustments applied, but RAW does not.  With a RAW file I can correct the white balance when editing the photos on my computer.  In fact, this is how I created the two example photos.  I was able to change the white balance setting on the RAW file to create the two different versions.  When shooting in JPEG mode it is very difficult to correct the white balance once the photo is taken.

When shooting in JPEG mode I will be aware of the color cast of the photo I'm about to take and decide if I need to override the Auto White Balance.   As I said, most cameras do a pretty good job on auto mode so this doesn't happen often.

Devices such as Expo Discs can be used to determine the color temperature of the light and creating custom white balance settings.  This is a more advanced topic that may get covered in a future post.