Shoot the Transitions

If you have followed this blog at all, you will have learned by now how I emphasize that photography is all about light...not the quantity of light, but the quality of light.  Quality light comes from many sources and is influenced by time, place, season, subject, angles, color, and intensity.  More importantly, quality light depends on you the photographer to seek it out and recognize it.

Recognizing quality light takes a bit of practice, but there are a few things you can count on to almost always find it.  One of the easiest is to 'shoot the transitions'.  Transitions are those times during the course of any given day when the light begins to change from one form to another...high to low, low to high, cool to warm, warm to cool, direct to filtered...and so on.  let me give you some examples.

The most obvious transition occurs at sundown when the bright and flat light of the day begins to drift toward a warmer, sometimes bolder, sometime more subtle, colors when the angle of the sun has to filter through a thicker part of the atmosphere.  Sunsets are also somewhat of a cliche...everyone photographs them and there isn't a sunset that has ever happened that hasn't been photographed somewhere...sometime.  I still find myself drawn to them, but I often instead photograph the effects of the sunset light as opposed to the direct sunset itself.  The soft warm nature of the sunset light casts a warm glow on everything it touches.  Sunrise on the other hand can offer an even more variety of transitional lighting conditions.  The predawn sky can vary from soft pastels to bold reds and yellows.  The trick is to use these color transitions within the context of time and place.

Although sunsets and sunrises offer the most common form of transitional light, other circumstances provide wonderful transitional opportunities.  Just before or just after a thunderstorm when the overcast is breaking apart or just gathering are two of my favorite transitional situations.  Some the most dramatic light is found where there are contrast of dark and light.  Dark and ominous skies offer great contrast of grays, blacks, and whites as they mix in the atmosphere.

Another often underutilized transition light is where bright beams of light contrast with darker surroundings...an example being inside a barn with light filtering through the cracks in the boards or under a canopy of trees when light penetrates to the floor.  Although difficult to generate correct exposure...they are not impossible problems.

Fog is probably my favorite transitional light.  I am always keeping tabs on the weather.  Here in Kentucky we have a lot of fog...and many times the first day or so after a rain the fog will develop in the low areas and across the fields early of a morning and sometimes right at dusk.

Transitional light does not have to solely be associated with the outdoors.  Reflected light bouncing off or through something is a type of transitional light as it is changed from direct light into indirect light.  Some of the best moody light is that mysterious reflected light illuminating a person's face against a dark background...or filtered light coming through and opaque object like glass or thin material.

Shooting the transitions will provide potentially wonderful quality light.  It's just a matter of anticipating ahead of time the conditions that might develop...and then being there.  Use transitional light to your advantage and you will begin to see a transition of your images from ordinary...to extraordinary.

Keith

The Mystery of Exposure - Part 3

One of the biggest mistakes novice photographers make is to believe that the camera will always give you a correct exposure for every lighting circumstance.

In part 1 we looked at the elements that make up the exposure triangle and followed up with a discussion in part 2 on how those elements work together.  In part 3 we're going to look at how the camera sees light and how the metering system applies the exposure values.

Have you ever returned from a vacation with a stack of photos to share only to have your friends quickly thumb through them..."Those are very nice..." they say.  Sort of deflating...as you say "Well...you had to be there...the pictures just don't do it justice."  There's a reason for that.

What we see visually can often be spectacular because of how our eye and brain work together to create an image in our mind.  We visually are able to distinguish between a wide range of contrasts, colors, and depths and are able to filter out all the clutter.  Contrary to popular belief, the camera does not see light the same way we visually perceive light.  A camera can only evaluate the intensity of the light that enters through the lens...then based on that evaluation make a programmed guess as to what the exposure should be.  That programmed guess is based on what is call the 18% neutral gray value.

The Thru the Lens or TTL metering systems built into cameras today are sophisticated computerized processes and will for the most part do a pretty good job of determining a workable exposure solution.  There are variations in the way they work, but all metering systems fundamentally do the same thing...They simply  take an average of the metered light and sets exposure values that are shifted toward the middle.  Remember the black to white light scale where the middle is a neutral gray.

There are three basic metering modes that TTL systems use:  Matrix or Evaluative, Center Weighted, and Spot.  Matrix/Evaluative meters the light across the entire spectrum of the view.  Center Weighted does the same thing except it places a higher value on an area concentrated around the center of the view.  Spot metering allows the photographer to meter off a specific area...or spot...like a face, or band of a distant hill...without  having the rest of the view skew the reading.  All three have their advantages and disadvantages.

Ninety percent of understanding the mystery of exposure is based on understanding how the metering systems work.  Using the strengths and weaknesses of each will give you an advantage when it comes to capturing those great shots.

Let me give you an example.  Take for instance photographing snow.  Snow is very bright and white.  Visually, even on cloudy days snow still looks white to us because our brain is able to recognize it as such.
But, the camera responds to bright white circumstances differently that what we see visually.

Allowing the camera to select the exposure will tend to make snow look a dingy gray (top image) as a result...think about it for a moment.  Why is that?  Well the camera doesn't know the difference between a snow field and coal field. The TTL meter wants to move everything toward the middle...or neutral gray.  Visualize the scale again...the white value of snow falls toward the outer white edge of the scale.  The camera wants to set an exposure that moves toward the middle...which is gray...thus white snow will often look gray as a result.

How do we get around that?  By using the Exposure Compensation (EV or AV +/-). This tool is something you need to understand and use.  On the back or top of most cameras you will see a button marked with +/-.  This button is used to trick the camera into shifting the exposure it wants to make, either more toward the lighter (+) or more toward the darker (-).  Going back to the snow scene...the camera wants to shift it toward the gray...you want it to look white...so...what would you do?

The plus (+) sign adds light to the exposure and the minus (-) removes light from the exposure.  To make the snow appear more white...you would have to add light to the exposure by using the + compensation.  Just how much depends on the circumstances...snow may require as little as +0.3 of a stop to more than one full stop higher (+1.0).  (bottom image)  Too much can create an over exposed situation...so be careful.

This concept applies to almost any bright (or dark) object including beach sand, buildings, birds, animals, even the sky..and to any color...not just black or white.  A dark red barn will have it's color shifted to a more neutral lighter red color...green grass is already a neutral color and will often remain unaffected...Are you beginning to get the idea? Just for grins...what would happen if you took a photo of a pile of coal ...very black.  You figure out what would happen and how you would compensate.  Understanding how the camera sees light and how to use the exposure compensation gives you a huge advantage.

This three part series was designed to get you to thinking about what the camera is doing and to use its capabilities to your advantage..not as a full blown workshop on exposure.  Even so, if this information helps you move forward, then the series accomplished its goal.  Todays cameras take a lot of the guess work out of the exposure process...but leave enough gaps open so you can begin to use the artistic flair that resides inside every photographer.  Knowing how to blend that artistic value with technical understanding is what separates the ordinary snapshot from artistically expressive images.

Keith

The Mystery of Exposure - Part 2 - B

In part one we defined the four parts of the exposure triangle...Aperture - Shutter - ISO - and White Balance. So now lets expand on that basic knowledge and see how everything works together.

Years ago before the advent of the light meter, photographers used a technique called 'The Sunny Sixteen Rule' to help them with their exposure settings.  The sunny sixteen rule works like this.  On as bright sunny day, the basic exposure is set based on ISO (ASA way back then).  If the ISO is 100, then the aperture is set to f/16 and the shutter is set to the nearest equivalent of the ISO or100...in most cases it would be 125th of a second.  ISO = 100 - Aperture = F/16 - Shutter 125th of a second.  This setting will produce an image basically the way the scene is observed and would be considered the photographers starting exposure from which they could make adjustments up or down depending on the results they wanted and the lighting conditions.

An important concept to understand is the concept of exposure equivalent.  Exposure equivalent works like this: Remember how the aperture scale works...as you go up the scale or use larger f/stop numbers, the smaller the aperture actually becomes...down the scale and the aperture grows larger. The basic aperture settings or f/stops are based on what are called full stop increments.  An f/stop of f/16 allows in half the light of the next lower down f/stop of f/11. F/11 is down the scale from f/16 so it is a larger aperture opening.  F/22 on the other hand is up the scale from f/16, so it allows in less light...exactly half the light of f/16.  Try to visualize this as you work up or down the f/stop scale.  From f/11 down the scale is f/8.  How much light does f/8 allow when compared to f/11....think about it now...well...f/8 allows in twice as much light as f/11.  As you work up or down the scale the same increments apply. Go up the scale, the light is halved with each full stop increment...down the scale, the light is doubled with each full stop increment. (most cameras today allow for less than full stop increments usually in 1/3rd stop, but the basic scale is set for one full stop increments between the f/stop settings.  Here's the basic scale:  f/1.4- f/2.0 - f/2.8 - f/4.0 - f/5.6 - f /8.0 - f/11 - f/16 - f/22 - f/32

(Do you see the pattern? Do you see how the factor of 2 applies?)

The shutter speed undergoes a similar progression.  1/15th of a second is twice as long as 1/30th of a second and using the same aperture the combination of shutter / aperture will allow in half as much light...in other words f/8 at 1/30th of a second allows in half the light as f/8 at 1/15th of a second.  Heres the basic shutter speed scale starting with 1/15th of a second:  1/15 - 1/30 - 1/60 - 1/125 - 1/250 - 1/500 - 1/1000. Again, most cameras allow for increments of less than one full stop between the basic scale settings...for instance between 1/500 and 1/1000 will fall 1/750th of a second or a half stop differrence.

Okay...so what does that mean.  Remember the sunny sixteen rule.  Under equal lighting conditions if you change the f/stop from f/16 to say f/11...what happens to the volume of light?  What happens then to the shutter speed?  To keep the same exposure equivalent, the shutter speed must increase or speed up.  Why is that?  Well, think about it. F/11 allows in twice as much light as f/16, so the shutter speed would have to increase to avoid overexposing the image.  From 125th of a second, the shutter speed would need to increase to 1/250th of a second.  What would happen if you went to f/8...where would the shutter speed have to go?...think about it...F/8 allows in twice as much light as f/11, so under the same lighting conditions, the shutter speed would have to increase again to the next full stop setting.

Sound a bit confusing?  It's really pretty simple once you begin to visualize what is happening.  Open the aperture to a larger setting, more light is allowed in.  When more light is allowed in, the shutter speed must compensate by speeding up accordingly to keep the same exposure.  Keep in mind that most cameras can increment the aperture and shutter in fractions of a full stop...something like 1/3rd intervals.

Maybe this will help.  F/5.6 @ 1/125th of a second will generate the exact same exposure as f/8.0 @ 1/60th of a second.  Why is that?   Exposure equivalents.  They both allow in the exact same amount of light..they are just using two different setting to accomplish it.  One uses a faster shutter speed with a larger aperture while the other uses a slower shutter speed with a smaller aperture...the end results are basically the same.  

The concepts just described were based on an ISO of 100.  If you change the ISO to say 200, what would happen?  Well, conceptually everything is the same, its just that your basic setting must adjust for the more sensitive ISO setting.  The sunny sixteen rule would shift only in that the starting shutter speed would change to the nearest equivalent to 200, or probably around 1/250th of a second instead of 1/125th.

One more quick concept before we move on.  Let's talk about Depth of Field.  Depth of field is a subject better left for a discussion on composition, but because aperture is a key component of determining the DOF I want to at least define it here.  DOF is basically that portion of an image that remains in focus from foreground to background.  Several factors affect DOF...focal length of the lens, distance from your subject, distance of the subject from the background, and aperture.  Simply stated the larger the aperture (f/4.0...f/3.5...f/2.8) the narrower the depth of field.  A small aperture like f/16 or f/22 will provide a very wide DOF.  A narrow DOF is an effective way to isolate your subject (top image) while a wide DOF is preferred when photographing landscapes because you want the foreground all the way to the background to be in focus (bottom image).

Okay...again space doesn't allow for an in depth discussion...but I hope part 2 at least gets you thinking more about what is happening when you start turning dials and pressing buttons on your camera.  The auto exposure process built into your camera basically follows the same rules just described and helps to take away a lot of the guess work.  The problem is, the auto exposure system doesn't always select the best exposure.  Theres a reason for that.  In part 3, we'll discuss how the camera sees light and how that affects the image results.  You just might be surprised to learn that the camera doesn't see light the same way we visualize light...understanding this is a key concept to improving your photos.

Keith Bridgman