推 wliu:白色的物體，就加ev就行了，配合ae-l，還有經驗 04/28 12:59
推 chrislux:多謝，很有幫助^^，所以是不是能測到灰色的就不需補償了 04/28 22:04
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作者: logi (要正面面對困境) 看板: DSLR
標題: Re: [問題] 測光的問題
時間: Sat Apr 28 20:09:58 2007
※ 引述《chrislux ()》之銘言：
: 先大概講一下我對測光的認知，有錯請大家糾正喔，
: 測光就是相機會依據測光錶的資料，調整快門和光圈，使曝光呈現約為灰色的18%
: 所以我的問題就是，為什麼需要測光測畫面中約為灰色的物體，
這樣會讓照片所呈現的和眼睛所見的最為一致
: 再來就是想問，用點測光應該要如何選擇測光的點？ (灰色的物體？)
測要拍攝的主體，譬如人臉，因為主體的亮度是最重要的
: 尤其主題是會動的，或是說白色比較多的，都讓我很困擾。
這時候平均測光比較好，若白色較多就增加曝光補償
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Typical scenes for Spot or Partial Metering
You should be aware of the followings points:
* Don't meter to the brightest spot of the scene - this would lead to
underexposed results. Try to find a place which has to be exposed right but
always think of the limitation of the metering system.
* Even spot or partial metering cover a substantial area of the picture
(up to 9.5%). E.g. the partial metering in the big picture (slot canyon)
above points to a very bright spot but it surely contains some of the
shadowed areas - in this special case it leads to a correct result.
* Normally print films can process a range of around 7 EV=f-stops (slide
film: up to 5 EV) so you should choose spots which are a little bit darker
than shown in the pictures above. If the amount of contrast in a scene
exceeds the limitations of the film your main subject will be outshined or a
"skyline"-effect will occure. You can use the latter as a stylistic element
like in the picture to the lower left (looks better projected than scanned).
Trick:
You can gain 1 EV by pre-exposing the film:
o switch to multi-exposure mode (#2)
o pre-expose with a high-shutter speed and small aperture to a
blank paper (e.g. 1/2000s, f/22)
o expose your picture (non-compensated)
"Black" will probably not as dense as normal but there shouldn't be any
further side-effects.