Photo How To

Even photographers who usually shoot in Manual Mode should take a closer look at Program AE Mode. Why? Because in the right hands, the two modes are more similar than they are different.

A couple weeks back this column explained the benefits of Aperture Priority and Shutter Priority exposure modes and why either is often preferable to shooting on Auto or Program AE. Here is the link. When the article was reposted on social media, many readers were kind enough to comment and several wrote that they prefer to shoot on Manual.

My hat is off to that hardcore group. The ability to shoot on Manual is clearly one of the reasons why we buy fully featured DSLRs. But I’m here to challenge you by saying that even when you shoot on Manual, you are shooting on Program.

Before you heat up the tar and fluff the feathers, hear me out. To shoot in manual mode, you must set both the shutter speed and the f/stop. Generally speaking, many people set the shutter speed first and then adjust the aperture to achieve the exposure they desire. Certainly some do it the other way around—aperture first and then the shutter speed. The point is, we usually set one first, and then the other. If we don’t like the combination—maybe because the shutter speed is too low to stop action, or the f/stop is too small or whatever—we simply change it.

The camera goes through exactly the same procedure when you select Program AE. It starts with a shutter speed that will stop action and adjusts the aperture to achieve correct exposure. In general, Program AE tries to shoot at a relatively fast shutter speed because it operates under the normally correct theory that most people have a hard time holding cameras still at slower speeds.

If the light changes, it adjusts the aperture. At a point predetermined by the program in firmware, it adjusts shutter speed and starts the process over again. In other words, the camera goes through essentially the same steps as an experienced photographer who is shooting on manual.

The difference is that on Program AE, the camera is fetching decision making data from a table that was created by a camera engineer. On Manual, the photographer is using his experience and whim. The disparity is threefold. The camera can do it faster, makes fewer mistakes and is more consistent scene-to-scene.

Program Mode Is Faster
The photo at the top of this article was shot on a Manhattan street with a Panasonic camera set on Program, ISO 100, 1/250 sec at f/5. I would have missed the expression if I’d tried to shoot Manual.

I am not saying that Program AE is better. Some gifted photographers are able to intuitively fine tune the exposure while shooting on M. I admire that ability. In fact, some photographers don’t even need light meters. My point is this: for many of us, in many situations, shooting on Program AE is a good option, and it does not mean giving up creative control.

Camera manufacturers are aware that not every program setting meets the needs of the shooting environment, photographer’s creative impulse and subject’s special requirements. So they have provided effective ways to provide photographers with creative control. The most prominent is called Program Shift.

To use Program Shift one simply changes the shutter speed or aperture. The other corresponding value changes automatically to keep exposure correct. For example, if the Program Slope calls for a setting of 1/250 at f/5.6 but the user wants more depth-of-field, the correct action would be to stop down the lens. If the user selects f/11 while leaving the camera on Program AE, the shutter speed will automatically drop to 1/60 second. Exposure is still correct, and camera is still set on P, but the user has exercised creative awareness—and control.

And hey—that sounds a lot like what happens when a Manual shooter makes adjustments. And that in a nutshell is my whole point.

Program Trivia
The first camera to have a Program AE function was not the Canon AE-1 Program as is commonly thought. Do you remember which model had the function built-in but undocumented? The Minolta XD-11, the world’s first “Dual Mode” (Aperture Priority and Shutter Priority) SLR, which first appeared in 1977.

When set to Shutter Priority, the XD-11 tried to achieve correct exposure using the shutter speed you selected. But if it was too dark (or too bright) it changed to something that worked. Although it was never advertised as such, the XD-11 had a Program Mode where the user picked the starting minimum shutter speed. Later, Minolta painted the “S” on the Mode dial green and encouraged users to set the camera on “Green for Go.”

For Beginners Only
When you shoot on Program AE, the camera achieves correct exposure by selecting the shutter speed and aperture (f/stop) from a predetermined table.  

To understand Program AE you must understand the fundamentals of exposure. The amount of light that reaches the imaging sensor is determined by two physical factors: the size of the lens opening (aperture, or f/stop) and the length of time the light is allowed to travel through that opening (the shutter speed). The sensor doesn’t care whether you use a small aperture for a long time or a large aperture for a short time, just so long as the net result is that the same amount of light reaches it.

In other words, it’s possible to achieve exactly the same precisely correct exposure using different combinations of apertures and shutter speeds. For example, you can shoot at f/2 at 1/500 second, or f/8 at 1/60 and either combination will yield correct exposure. However, which combination you choose can have a profound effect on your image.

But that, as they say, is a subject for another day.

—Jon Sienkiewicz