Remember how exciting it was to get the training wheels off your first bike? Free of them you could lean into turns, seemingly defy gravity, and enter a whole new world of exploration. Of course it came at the price of possibly flying over your handlebars and landing on your face!
Modern cameras have such nice training wheels that many never take them off. The camera calculates exposures that work fine in many situations and keep us from making flying over the handle bars mistakes. But it also limits our creativity. The camera has no clue that overexposing your backlit cat might create an angelic look. Or that underexposing your candlelit dinner might perfectly convey the mood. It doesn’t even have a clue that you care more about the texture of your black dog’s fur than the detail of the snow he’s standing on.
Those training wheels are great for getting us started and building confidence. But it’s time to take the wheels off and tie together what we’ve learned these past two months. We’ll still let the camera decide how much light should hit the sensor or film. But let’s tell the camera how to balance its two main exposure controls — shutter speed (the duration our film is exposed to light) and aperture (the size of the hole the light comes through).
Two months ago we discussed action photography and the importance of shutter speed in freezing motion. We learned to use a fast shutter speed to freeze the motion of a running dog — exposing as quick as 1/2000th of a second. To create artistic blur we left the shutter open much longer.
Last month we discussed how a wide aperture produces a very narrow depth of field, allowing us to take a photo with our dog’s eyes in focus and everything else blurred. We learned that a narrow aperture produces the deep depth of field we might use for a landscape where everything from close in trees to far off mountains is in sharp focus.
Most times there are many possible combinations of aperture and shutter speed that will produce a well exposed photo. But in automatic mode you’re stuck with whatever tradeoff your camera thinks is best — whether that’s a fast shutter speed and narrow depth of field, or the opposite. Happily, many cameras let you control the tradeoff using an Av (Aperture Priority) or Tv (Time Priority) mode. In Av mode you tell the camera what aperture you’d like — in effect, shallow or wide depth of field — and it calculates the length of exposure needed.
The way I often use this mode is to select my desired aperture and then see if the shutter speed calculated will work for me. If not, then I either try a different aperture or change the ISO setting (which we’ll discuss in the future). The key is that I’m choosing, not the camera.
Knowing what tradeoff to make comes with experience — which you’ll gain by controlling the balance between aperture and shutter speed yourself. Lighting conditions won’t always let you have exactly what you want, but you’ll be choosing what to give up — and before long you’ll be making cool, creative photos that a camera couldn’t create on auto.
This month’s assignment is to create a photo using Av or Tv mode. Use any setting you like — the goal is to experience the relationship between shutter speed and aperture. If your camera doesn’t have those modes then pay attention to the shutter speed and aperture the camera chooses and try to predict the results — considering motion blur and depth of field. I look forward to seeing your results and hearing about your experience!
David Childs is a professional photographer, photo journalist, instructor, and animal advocate. You can see his work or contact him at www.DavidChildsPhotography.com.