講一大堆嘢不如大家睇睇 Wikipedia 對 Exposure Value 的解說: EV = log2 (N^2/t) - (1); N^2/t = LS/K - (2); EV = log2 (LS/K) - (3); where, - N is the relative aperture (f-number), - t is the exposure time ("shutter speed") in seconds[2] - L is the average scene luminance - S is the ISO arithmetic speed - K is the reflected-light meter calibration constant 睇完咪了解光照, 光圈, 快門, 和ISO的關係. 在數碼年代, 都要講清楚光圈, 快門, 和ISO對特定的光照上的應用.
EV was originally developed during the film photography days, ISO can only be changed if one changes the whole roll of film, so the calculation of EV was not involving ISO. When I first learned about photography in the 70’s, my control of exposure was by shutter speed and aperture, changing film was for low light condition and film characters such as graininess.
@alexngphoto29 күн бұрын
Thanks for your detailed explanation of the history of EV.
@starleo4126Ай бұрын
07:20,嚇,EV0係咁解釋? ChatGTP佢係咪誤會左亮度同EV係唔同既野?
@alexngphoto29 күн бұрын
佢講緊LV
@dennyfung5661Ай бұрын
EV 值應如音响的db,0db和0EV都是一用於對比的參考值,是沒有絕對值,增減EV值或db是相對於0db或0EV
@alexngphoto29 күн бұрын
😅我唔識音響
@harryfarmingwon4301Ай бұрын
5分15秒的 AI 解釋是正確的。EV (曝光值) 是在幾十年前定義,當年我們使用菲林相機,EV是作為攝影師的參考。135菲林普遍是用 ASA100,即 ISO100。我們不能在同一卷菲林上更改ISO,所以制定EV時採用了一個固定基數,就是 ISO100。 如今我們使用數碼相機,可以為每一張照片更改ISO。ISO 與 EV 值直接相關。當 ISO 改變時,曝光值必須相應改變,以達到正確的曝光。它們是相互關聯的。 看看曝光三角,我們不能忽視ISO值。因此,很抱歉地說,這段視頻中的解釋是錯的。
@alexngphoto29 күн бұрын
😂 你知唔知道除了EV,還有LV ?
@harryfarmingwon430129 күн бұрын
@@alexngphoto LV 是絕對光強度 (absolute light intensity),而 EV 是快門速度和光圈的組合。兩者都舆菲林速度相關;在 ISO100(DIN21)時,它們的數值是相等的。
@marychan123429 күн бұрын
簡單啲用實例去看 EV 值是否舆 ISO 有關,如果陽光下用 EV13 影一張相,set ISO100 影出來的相片是正常,但改用 ISO400 就一定爆光。
Introducing ISO to EV is called LV (light value) instead, similar concept, more applicable to photography, easily confused.
@alexngphotoАй бұрын
LV更少人用,可以稱为照明值,就是用ASA100做Base
@kampuiching482Ай бұрын
老師,EV 值係光圈同快門嘅對數,一去到數學,就真係有啲麻煩去解釋
@alexngphoto29 күн бұрын
確實係難講,因為受眾的理解力參差
@usei229 күн бұрын
科技令好多野簡化左好多 唔洗識咁多理論 去提升藝術素養 / 多學一些技巧會更實用
@latitude3695Ай бұрын
thx
@longthepianistАй бұрын
Any attempt to understand EV number is futile unless one fully understands what Correct Exposure as seen through light meter means. Correct exposure simply means exposing a sufficient amount of light to light sensitive materials such as a piece of film or sensor that will result in properly reflecting 18% gray, which is when using the light meter precisely measuring a specific part of an image. Correct exposure is determined base on these three factors: light sensitive material (film or sensor's graded iso), aperture and shutter speed. You can choose to over or under expose, that's your artistic choice, and it also takes practice to make it become your second nature. There are many modes to choose from when using a light meter to measure, kind of annoying but the one you really want to learn to use, and can grow from, is the spot metering mode.