Wednesday, May 27, 2015

Aperture Priority vs. Shutter Priority

Telephone - San Simeon, California
I used Aperture Priority Mode for this image because I wanted a certain depth-of-field.
In yesterday's post I said, "The 40mm lens is my primary lens for this camera and I use it 90% or more of the time. However, on this trip the 55-200mm lens got the bulk of the load. Because of that, instead of using the camera in aperture priority mode, I found myself using shutter priority mode more than ever before."

Someone wanted to know why I would choose aperture priority mode or shutter priority mode and what that even means.

Aperture priority and shutter priority modes are semiautomatic functions commonly found on digital cameras. Sometimes the names are different and the exact way that they work can vary, but on most cameras they're basically the same. When in aperture priority mode, you choose the aperture and the camera chooses the shutter speed and the ISO. When in shutter priority mode you choose the shutter speed and the camera chooses the aperture and the ISO.

These semiautomatic features allow the photographer to have control over an aspect of the process that they need to control, and let the camera worry about the other aspects that the photographer doesn't care so much about. They speed up the process for the photographer.
Steadfast Movement - Mojave, California
I used Shutter Priority Mode for this image because I wanted to show motion.
Typically, for most of my images, I want to control the aperture. The aperture affects depth-of-field and (to an extent) sharpness. When in aperture priority mode, the way that I have the camera set up, the shutter speed doesn't go any slower than 1/125 unless the maximum ISO (which I set at ISO 3200) is achieved. I set the aperture to what I want and the camera figures out what the shutter speed and ISO should be within the parameters that I've set.

Sometimes, though, I want to control the shutter speed. Most often it's a situation where I want a shutter speed slower than 1/125 to show motion in an image. But sometimes I want a shutter speed faster than 1/125, such as when I want to freeze motion or I'm using a telephoto lens. Camera shake is magnified with a telephoto lens, so a faster shutter speed or tripod is required to get a sharp image. I could go into the menus and adjust the auto-parameters that I've set up, or (more easily), I can switch the camera to shutter priority mode. I lose control over the aperture (although I can still manipulate the aperture a little), but I gain control over what I most want to control.

Occasionally neither of these semiautomatic modes are ideal so I go fully manual. This is no big deal and I have a few different film cameras that I sometimes use that don't have any auto modes. Auto-features just allow me to more quickly achieve what I want, but they're only useful when they allow me to accomplish whatever it is that I'm trying to accomplish.

So the reason that I used "shutter priority mode more than ever before" is because I was using a telephoto lens and I left the tripod behind. I wanted a faster shutter speed and I didn't care quite as much about the aperture. Simple enough.

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