Saturday, April 11, 2009

Manual Camera Controls

All cameras once had focus, shutter speed and aperture as manual control mechanisms. Over time camera designers realized that by making these automatic, cameras could be sold for less money and more people would find cameras easy to use. More expensive cameras offer the option of both automatic and manual operation. Although it is often not critical to have manual access to these controls, having access to them opens lots of new visual possibilities. Placing a subject slightly out of focus or way out of focus can be interesting since this is not a capability our eyes have to the same extent. Being able to manually control shutter speeds makes it possible to freeze motion and blur motion. Changing the aperture changes how much is in focus other than the main subject.

Controlling the focus is done by moving the switch on the side of the lens from AF (or Autofocus) to M (or Manual) and rotating the lens barrel to the desired focus.

To change the shutter speed, go to the dial on top of the camera. This is called the Exposure Mode Dial. There are 4 adjacent settings. On some cameras it is P S A and M and on the rest it is P Tv Av and M. Choose S or Tv depending on the camera. This allows one to choose any shutter speed while the camera automatically chooses an aperture that allows the correct amount of light to hit the sensor so that the photograph comes out just the right brightness. On the top front of the camera there is a sub command dial. On my camera this is a small wheel directly in front of the shutter release button. At the top of the Digital Control Panel two numbers appear side by side. The one on the left is the shutter speed. The one on the right is the aperture. By turning the camera on and pushing the shutter release button half way down the panel should light up to show the shutter speed. By rotating the sub command dial the speeds should change. One and two digit speeds require the use of a tripod to get a sharp focus. One and two digit speeds will blur motion and three and four speed numbers will freeze motion. This is most visible when the subject is going across the picture.

To change the aperture go to the Exposure Mode Dial. Choose A or Av depending on the camera. This allows one to choose any aperture while the camera automatically chooses a shutter speed that allows the correct amount of light to hit the sensor so that the photograph comes out just the right brightness. At the top of the Digital Control Panel two numbers appear side by side. The one on the left is the shutter speed. The one on the right is the aperture. By turning the camera on and pushing the shutter release button half way down the panel should light up to show the aperture. By rotating the sub command dial apertures should change. Small numbers provide a minimal range of focus and large numbers provide a maximum range of focus. This is most visible at close distances. It is very important to watch how the camera chooses the shutter speed. If the camera chooses a one and two digit speed the use of a tripod is required to get a sharp focus.

A good way to simulate shutter speed and aperture changes is to go to http://www.photonhead.com/simcam/shutteraperture.php

All text unless otherwise noted is ©2009 Paul Light. All rights are reserved.

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