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Old Dec 23, 2005, 3:40 PM   #1
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I havea 350D or Rebel XT.

So I understand that the DOF preview button is modifying the aperture in the lens to indicate the amount of light coming into the sensor, and it makes the display go darker, but what I don't understand is how do you "read" or understand what it shows you? So it goes dark? Whoopy doo... should it? Do I need to open the aperture further? I really don't understand if this tool can be useful or not to me. As I have usually found out the manual is pretty useless!

Please can somebody give me an explanation!


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Old Dec 23, 2005, 4:30 PM   #2
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It stops your lens down to the aperture you'll be using to take the photo. It's difficult to see, but it will show you what in your frame will be in sharp focus, it's difficult to see because when the lens is stopped down, the frame gets darker. This photozone page illustrates this very well: http://www.photozone.de/3Technology/demos/DOFbutton.htm

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Old Dec 24, 2005, 12:40 AM   #3
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Set your camera aperture to f16. Turn it around and look into the lens. Press the preview button.

You will see the aperture close down.

When looking through the viewfinder it gives you a (very poor) indication of how much of the frame will be in focus when you press the shutter.

Frankly it's a feature that I only find useful for amusement value when doing exactly as described above.

There is some flash feature that makes it useful apparently - NHL explained once before, but I don't do flash much atm, so I've forgotten. :P

I'm planning to take a portrait lighting course next year so maybe then....
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