Martin@SEPHIROT
註冊: 2004-03-03
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Re: 點解有時影d相會咁曚ge.. Post time: 3 月 6 日 |
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1) Image blur.
Image blur can be caused by hand shake or an out-of-focus image.
2)光圈
Aperture controls the amount of light entering the lens, it also controls th depth-of-field(景深). It can be set to different number. The smaller number represent a wider opening, allowing more light entering the lens at a time. A small number setting close the aperture and allowing les light entering your lens.
3)ISO
ISO is the light sensitivity of your film, or CCD in digital. A low ISO setting requires more light to take the picture, and give a smoother picture with more detail and color. High ISO setting will decrease image quality, increase image noise, but requires less light to take the picture.
4)景深
Depth of field is controlled by aperture and focal length.
As we are living in a 3D world and photo is a 2D art. We have to "put" 3D into 2D when taking photo.
In 3D, we can define distance, but in 2D, we can only define depth of field.
Imagine you are in a picture, standing between a flower and a tree, with flower in front and tree at back. The picture is focus on you.
A shallow(small) depth of field can just put yourself in focus. The tree and flower is blur.
A deep depth of field should make all 3 sharp enough.
A long focal length lens and large aperture make shallow depth of field.
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