Most folks have heard or read about the “Exposure Triangle,” the holy trinity of photography. ISO, Aperture, and Shutter Speed fit into each of its corners. These three controls of light are important to understand for what each affects and many have written about those things, including me (http://www.infotor.com/blog/reciprocity-and-the-triangle/). 
The most important thing to understand about these three controls besides what they each affect in your images is how to balance them properly to get an image exposed to your liking. That may not be a “correctly” exposed image, as Bryan Peterson likes to say, but it will be a creative one based on your judgement calls on the exposure.
When we add flash to the mix, I have thought in terms of two exposure triangles (http://www.infotor.com/blog/reviewing-flash-basics-firming-up-the-foundation/), one for the available, ambient light - most affected by shutter speed - and the other for flash exposure. In this second triangle, flash power replaces shutter speed. I’m rethinking that as a Square. After all, a square contains two triangles fit together. Right? Right!
Visualizing the interplay of controls as a square makes perfect sense to me as ISO and Aperture, at opposite corners of the triangle, affect both the ambient and flash exposure of your scene. On the two other opposing corners lie Shutter Speed and Flash Power. Shutter speed is in the “ambient shot” area of our square since it only affects how much ambient light will be visible in the resulting image. And, in the other half of our square, the “flash shot” area, Flash Power affects how illuminated your subject in the scene will be. That is, Flash Power together with Aperture and ISO determine how bright or dark the subject will be. The best real life example of this is when you have a brightly backlit subject so that when you meter the exposure using only your camera’s built-in meter, you end up with either a real blown out background or, and more likely, a wonderful black silhouette of your subject! When we add flash to the mix, we first take a meter reading so that our background - trees, a beach, a view from an overlook on a sunny day - is perfectly exposed. Then we turn on our flash and take the shot. If our subject is too bright, we adjust either our flash power or our aperture in Manual flash mode and Manual Shooting Mode. The result should be a perfectly exposed background and a perfectly exposed subject!
There are, however, other controls we can add to affect the outcome of our images. We can use a circular polarizer filter to reduce glare on our subject(s) caused by the sun or our flash. We can limit the amount of ambient light, too, by using a Neutral Density Filter, a fader. Now we have six different potential controls to affect the light that falls on our scene: aperture, ISO, shutter speed, flash power, a polarizer, and a fader. Rod Deutschmann of IFLC San Diego Photography Courses and his wife Robin have come up with a third geometric figure to represent this more complete picture of what influences the outcome of an image: the Hexagon of Creative Choices: http://bit.ly/IFLCHexagon. As Rod says, “a flash adds light, a fader takes it away, and a polarizer cleans it.” By incorporating these three additional light controls into our geometric graphic of what can affect our images, we create a whole new tool and way to think of what is possible when we want to make an image.
Deutschmann presented this approach the other day in a post to the IFLC Facebook page and it has really gotten me thinking about how we all approach our photography. I have changed mine drastically in the past two years. I now put much more emphasis on having full control. I shoot in the Manual Shooting Mode most of the time and encourage my students and tutoring clients to do the same. Once you have a good foundation shooting in Manual, switching to either of the Priority modes is easy. Plus, you gain a much better appreciation for how the first three elements of photography that give you control over your exposure work together. With his presentation of the Hexagon idea, Deutschmann has me rethinking things once again. I have become quite comfortable applying flash to my image making and really appreciate the difference it can make in the results. I occasionally use a polarizer filter to reduce or eliminate glare on my subjects - usually plants and green leaves - but I have not made its use a real part of my image making beyond that. I have faders for almost all of my lenses and, once again, I don’t use them much at all. I plan to revisit their usefulness and begin incorporating them into my everyday shooting. The end result of doing this, as usually happens, will be a revision of how I present photography to my students and tutoring clients I am sure.
Just goes to show you. There is always something new to consider and learn! I love that!
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