近日收到不少網友意見，指 DCFever.com「吹水閒聊」充斥愈來愈多粗言穢語、人身攻擊、誹謗等不理性討論。作為 一個以攝影興趣為主題的網站，此等漫罵式討論已超出 DCFever.com 設立討論區之原意。DCFever.com 呼籲大家以 攝影交流為目的作理性討論，並正密切留意事態的發展。
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d2c
註冊: 2005-05-05
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 DSLR 點 解 可 以 AF ????? Post time: 3 月 28 日 |
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會員戶口已被刪除，資料已被標示為不顯示
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Rol
註冊: 2004-09-15
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| Re: DSLR 點 解 可 以 AF ????? Post time: 3 月 28 日 |
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I have very little knowledge in AF and DSLR structure.
As I know, the light come from Lens is not all go to optical viewfinder, part of light is reflected to the detector for AF and expo metering. So some people guess that D70 / 50 with smaller viewfinder because it take more light to AF detector for faster and more accurate focus.
Pls correct me if any wrong.
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walkingfuture
註冊: 2002-11-14
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| Re: DSLR 點 解 可 以 AF ????? Post time: 3 月 28 日 |
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All DSLR (SLR) has a seperated sensor working as an AF sensor and metering sensor. Just at the top side.
So, it's totally different from normal non-DSLR DC, non-DSLR DC will do all the things (AF, metering, taking photo..etc) on the same sensor.
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d2c
註冊: 2005-05-05
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| Re: DSLR 點 解 可 以 AF ????? Post time: 3 月 28 日 |
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會員戶口已被刪除，資料已被標示為不顯示
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d2c
註冊: 2005-05-05
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| Re: DSLR 點 解 可 以 AF ????? Post time: 3 月 28 日 |
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會員戶口已被刪除，資料已被標示為不顯示
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akirabbq
註冊: 2004-07-06
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| Re: DSLR 點 解 可 以 AF ????? Post time: 3 月 29 日 |
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The AF sensor are NOT on the top side, it is at the bottom under the mirror. However metering sensors are on the top side, behind one of the sides of the pentaprism/mirror.
Believe it or not, the main mirror is semi transparent, so some light can pass through the main mirror. There is a second mirror behind the main mirror, which reflects light to the AF sensors at the bottom.
DC uses CCD for live preview, AF and metering can be computed by live data fed from the sensor. When a DSLR has its mirror up, there is no way to meter and AF, except using the same method as a DC, but this will increase the cost of the DSLR. That's also why E330 can not do AF when using LCD to preview.
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