20071031/如何用数码相机拍摄电视画面

Take TV Pictures
Taking pictures from the television screen using your digital camera is quite easy.

If you have ever tried taking pictures straight from your television screen, you might have sometimes noticed horizontal lines running up and down the picture. That is because a TV screen is “painted” one pixel at a time from top to bottom. The lines appear on your pictures when you use a shutter speed that is too fast and that “freezes” the lines on the television image.

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Kodak Easyshare DX6490
Shutter-Priority mode, Spot
9.8mm, 1/90 sec., F3.2, ISO 80

In this One-Pager? tutorial, we’ll give you the one simple trick that you need to know to be able to take television picture using your digital camera. Ready? All right, simply use a shutter speed of 1/30 sec. and preferably slower. The idea is to use a shutter speed that synchronizes with the the painting of the TV image and voila — no moving horizontal lines.

You might want to experiment with different shutter speeds, such as 1/15 sec., 1/25 sec., (but less than 1/30 sec.) to see where you get optimum quality on your TV using your digital camera. Of course, to be able to set the shutter speed on your camera, you need to be able to switch to Shutter-Priority mode. The following pictures were taken with the Kodak Easyshare DX6490, and I find that a shutter speed of 1/15 sec. is optimum. With 1/30 sec., a few lines is apparent at larger image size.

For images of a computer screen, try 1/20 sec. and slower, and get a meter reading directly from the screen.

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Dora
Shutter-Priority, Spot
9.8mm, 1/15 sec., F3.6, ISO 80

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Max & Ruby
Shutter-Priority, Spot
9.8mm, 1/15 sec., F5.6, ISO 80

dc4.jpg
Smallville
Shutter-Priority mode, Spot
11.5mm, 1/30 sec., F3.2, ISO 80

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Star Trek Enterprise
Shutter-Priority mode, Spot
11.5mm, 1/30 sec., F3.2, ISO 80

What if your camera does not allow you to set a shutter speed directly? Well, then you have no choice but to experiment. For example, try one of the scene modes. Or, try this very arkward experiment::
– take a couple of pictures in the room (not of the bright TV screen)
– upload to your PC and look for a picture where the EXIF info says a shutter speed of 1/30 sec. or whereabout was used
– go back and lock your camera’s light meter at that subject [must be same distance from subject as you will be from TV because AF will usually also lock] by a half-press of the shutter button
– then recompose on your TV screen and take the shot at the locked exposure.

We hope you have enjoyed this tutorial. If you have any questions, spot any errors, or have an article idea, please give us your feedback on this article. We will publish as many comments here as we can.

http://www.photoxels.com/tutorial_tv.html

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