In Praise of Program Shift

Getting the most out of automation: part 5

1/320th sec. @ f3.5

Program Shift: some of the more sophisticated P&S cameras on the market today have a very powerful feature called Program Shift. If your camera has it, then this article is definitely for you. Even if your camera does not have Program Shift, this article will reinforce much of what has already been discussed around exposure…especially f-stop (aperture) and shutter speed and how they relate to how the image is captured.

You may remember this diagram from Get With the Program: Exposure 2.

I asked you to imagine the arrow swinging around the correct exposure point. Any combination of f-stop and shutter speed that can be connected through the correct exposure point will provide the exact same light level on the sensor, and the same exposure of the scene. Since WordPress does not allow embedded flash, click here for a little animation.

Exposure Visualized and then come back to this page.

Once you have the relationship between shutter speed and f-stop around any given exposure level in your mind, then it is easy to understand Program Shift.

For an example I am going to use my Sony DSC H9. Even if your camera has Program Shift, it may have very different controls or settings, menus, etc. to activate it. Consult your manual. This article will give you the basic principles but the details may be different for your camera.

On my H9, when you are in Program, Program Shift is automatically activated. Across the bottom of the LCD there are several parameters you can control directly using the scroll wheel to the right of the LCD. Program Shift is in the center and is the default. To select one of the others, you have to click the center button in the scroll wheel and migrate to the other parameter. Turning the scroll wheel without hitting the center button first shifts the program. Automatically.

I actually find this a excellent choice on the part of the Sony designers.

Note the numbers inside the red circle (added…the circle is not part of the display). These numbers represent the current exposure settings the program has chosen. In this case 1/40th of a second (shutter speed) at f2.7 (aperture). The inside light where I took the picture was just average unaided inside daylight so the aperture is wide and the shutter speed is fairly slow. In fact f2.7 is the widest aperture the lens is capable of.

The yell0w indicates that these are the parameters the scroll wheel is currently controling.

The scroll wheel is shown inside the red box above. Turning it shifts both the f-stop and the shutter speed to maintain the same exposure.

In this image I have shifted the program from 1/40th at f2.7 to 1/35th at f3.5…selecting a longer shutter speed and and a smaller aperture (remember, larger f-stop numbers represent a smaller aperture and less light, and, though it doesn’t seem logical to those of us who don’t think in math, 1/35th of a second is actually longer than 1/40th).

Why would I want to do that? Well, I might be taking a picture of, say, a group of stationary objects at a fairly close distance, not all of which are the same distance from the camera.

Remember these two images from a previous discussion. The second was taken at a smaller aperture than the first…it has greater depth of field, so that the foreground and background figures are slightly sharper than in the first. I used program shift between images.

On the other hand, I might be taking an image of a moving subject. In the example above, I would want to increase the shutter speed to stop the action. In this light, however, I am already at my largest aperture…program shift will not help me since there I can’t increase shutter speed without changing the exposure. (I might, in this case, shift my ISO to a higher setting than the program mode selected for me, just to see if that helps…but that would not be done with Program Shift.)

Some program shift examples.

1/300th sec. @ f2.7 notice the softness near and far

program shifted to 1/40th sec. @ f8: increased sharpness near and far

1/100th sec. @ f8: notice the softness especially when compared to this…which has been program shifted to 1/400th sec. @ f4.5.

Which you prefer is an aesthetic choice.

bridge: 1/300th at F8

Corner detail from 1/400 @ f8

Corner detail after a program shift to 1/1600 @ f3.2

Notice on this one, that the purple fringing (sensor artifact) and chromatic aberration (green and magenta fringing, a lens artifact) are both reduced at the smaller aperture. Look at the edges of the post in the foreground.

Finally, the classic program shift situation: the portrait.

confusing background 1/10 sec. @ f7

Program shift to 1/50th at f3.2 to soften the background.

There are other ways, of course, to achieve the same effects, and I have chosen program shifts at the far extremes of what my Program and camera can provide. There are a full range of other settings in between which are not illustrated.

Let’s end with another classic opportunity for using Program Shift to change the expression of a scene: rapidly flowing water. Some like it crisp and sharp, frozen in motion, sculptured light: as it is at the head of this column, 1/320th sec. @ f3.5.

Some like it smooth and blurred, expressing a motion too rapid for the eye to follow. With Program Shift you can easily shoot it both ways…with just a twirl of the wheel. Like this:
1/13th sec. @ f8