[KT2608]

我用300d 去影相時, 經常會影到整件白衫好像放光一樣, 完全看不到衫上的口袋及花紋，但其他部位則曝光正常。請問可怎樣改善？

[rtao]

影白色野要見到details, 一定要-EV.....

[neu]

use nd filter la ...

[KT2608]

What is "nd filter"? And what is its function?
Many Thanks!!

[calvinchiu]

小弟淺見..
可否用 spot-meter to point to the face of object?

[micros]

用 ND 無用喎﹐又唔會只係減白衫﹐係全部都減。
如果其他地方都NORMAL﹐咁只有就 UNDER少少影﹐事後係 PS 執。

[neu]

"... 用 ND 無用喎﹐又唔會只係減白衫﹐係全部都減。
如果其他地方都NORMAL﹐咁只有就 UNDER少少影﹐事後係 PS 執。 ..."

that is exactly the function of using ND filters, it is focused to reduce excessive light without affecting the rest. "...又唔會只係減白衫﹐係全部都減..." is just TOTALLY BULLSHIT. ND is not any color filter, it is like sunglasses to the lens.

micros, if that was your perception/assumption of ND, take my advice, spend some time on learning photography again, pls!!! if you do not know how to use this simple filter, of course, you would spend more & more on Photoshop to compensate your inaduquate knowledge in photography.

http://www.dcfever.com/forum/read.php?f=7&i=6397&t=6397&phorum_auth=f11b3cc530fbc96c08fffe900143833a

kt2068, pls read reference book on this subject, or at least do a search on the keywords "neutral density filter", you can go to kodak 's homepage to get some info as well.

[stanleyy]

小弟覺得用ND未必可以解決這個問題, 因為用ND減少光線進入...但300D係用鏡後測光, 所以300D會只會以為入光少O左, 自己會加返大快門或加長曝光時間(如果用AUTO/TV/AV), e.g. ND+2, 300D會加返一級曝光, 結果曝光率係一樣... -EV 都係一個好方法... 不過CALVINCHIU講得對, "spot-meter to point to the face of object" 係最正路, 因你係影個人嗎! 更係要個人曝光正常啦. (不個300D無SPOT-METERING, 得個PARTIAL (9%), 好過無) 如果你"其他部位則曝光正常" 但又唔想"影到整件白衫好像放光一樣", 咁PHOTOSHOP似係你唯一出路.

......個人意見, 如對各位有什?得失, 請見諒... :p

[KT2608]

Thanks for all your kindly advices.

I am a freshman to photography, but I am really "serious" to it and surely I will read more books.

[neu]

for your reference:

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/filter-ND.html

i think what kt2608 wanted here was to deal with the EXCESSIVE LIGHT, provided that the most suitable exposure value is already calculated & decided.

of course, getting the right exposure of the face is important when doing portrait. but the problem is what happens to the white shirt under bright sunlight? there would be poor/no texture at all. so n.d. is the way to deal with the situation WITHOUT CHANGING THE REST (esp for shadow details). sure, you can -ev to make the shirt look darker, but when doing so, what happen to the face? don't you think it would be darker than you priviously wanted? that is the point of using ND! just -ev will affect the rest in the picture.

"... without a camera that have spot metering...". does that mean you can't have an accurate exposure of the face of a subject?

1. why not get a bit closer to do the calculation? try to cover the metering area with the face for calculation, then step back to where you were and shoot?

2. another suggestion: switch to a tele lens (provided that you have one with you) and use it for exposure calculation. tele lens has narrower angles when compared with wide angle lens. you can use it for better metering (a more narrow metering). then switch back to the lens you were using and shoot.

3. using a grey card (reflects 18% of light) is the best way to get the right exposure. but here, you need to think in b&w photography (tone control, zone system). do you want the face to be as in zone 5? or if that is a female subject, then do you want her to have a lighter skin tone? light than zone 5? or a tanned skin tone? you can use the grey card as a start to change the exposure as you prefer.

the above suggestions are made based on the experience of using film camera. i don't think ppl need the most fanciest camera to take good picture. think more, and there are always ways to solve technical problems.

[neu]

i suddenly know what you guys meant by this:

"... 因為用ND減少光線進入...但300D係用鏡後測光, 所以300D會只會以為入光少O左, 自己會加返大快門或加長曝光時間(如果用AUTO/TV/AV), e.g. ND+2, 300D會加返一級曝光, 結果曝光率係一樣... "

using a nd filter, you need to get compensation for exposure! (check the tables of nd filters) but that would not affect the rest, it is a weapon to deal with excessive light. e.g. when use 0.6 gelatin nd filter (for 1 e.v. over), you need to compensate 2 f-stops. but the problem of overlit white shirt will be solved. the texture will come back. try it then you know what i am talking about.

[micros]

可能係我膚淺﹐又或者大家根本唔係講緊同一樣o野。
我所用過o既都係全幅減光。局部減光ND係有﹐除O左影magic﹐好少見人用。

我只知道唔影響色調﹐無聽過只減光位唔減暗位。
http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/filter-
ND.html
睇番呢個 site 最下三張﹐最大分別係景深﹐其次係o的色改變o左少少﹐最重要係隻獅子光位同暗位分別不大。8x應該係三級﹐但我見﹐光位幾乎一樣﹐無暗到。文字亦無講過只係減光位。我係另一O的網頁就提到:

http://www.npc.org.hk/chi/article/basic/art11.php
簡稱ND，中色濾光鏡對各種光的吸收率相等，是用來減低通過鏡頭的光量。當使用最小光圈或最快快門，還曝光過度時，便需要中色濾光鏡來減低曝光值。它分為二倍、四倍、八倍三種，所謂的倍數是只曝光倍數而言。

http://www.thkphoto.com/products/hoya/oef-05.html
ND filters appear grey and reduce the amount of light reaching the film, they have no affect on color balance.
留意﹐係color balance。

用 ND﹐只係改變O左曝光組合﹐對整體曝光同光差都無改變。我唔知況且﹐係唔覺得只係只減光位唔減暗位好有問題﹖個 STANDARD係點﹖條線係邊﹖係邊個位以上先會減﹖AI 人工智能 ND 鏡﹖

想問一句﹐你 ...... 用過未 ...... ﹖
定係有誤會﹖

[micros]

講錯o左﹐修改一下。

用 ND﹐只係入光量改變o左﹐因而要改變曝光組合﹐對整體光差都無改變。況且﹐你唔覺得只係減光位唔減暗位好有問題﹖個 STANDARD係點﹖條線係邊﹖係邊個位以上先會減﹖AI 人工智能 ND 鏡﹖

仲有就係請專業o既 neu 朋友﹐無論係幾專業同英文幾好﹐都﹐請你﹐唔該﹐即使我玥講錯﹐可唔可以唔好用「just TOTALLY BULLSHIT」。討論下o者﹐唔使咁重語氣﹐可能你係老外慣o左﹐不過呢度唔係﹐咁重語氣衰 o左好難返轉頭。

[KT2608]

What makes photography so fancy? Because we can use poor "instrument" to take great photos!

Although we may encounter different difficulties in taking photos, we can solve it by some smart trick! How funny it is!!

Really thanks!!

[lungdungyee]

反射式測光表(即相機中的測光系統)對白色應該是UNDER, 因為白色反光比綠色多, 在同一光源強度下, 理論上測了白色來影應該使其他地方UNDER EXPOSURE 1.5EV 2EV之間.
推斷是: 您應該測了不是白色地方吧!
個人經驗, 採用下手段按測光值解決:
(1) 取平均測光值, 先測主體(如面部),再測白衫,如UNDER 1.5-2EV 是正常. 可以選取平均值再加工(以前菲林曬相處理叫"燒相"-局部OVER/UNDER, 現今DIGITAL執相 更容易解決).
(2) 如面部與白衫一樣( 即是白衫是OVER 2EV, 就算用DIGTIAL執相 返魂無術), 一是用反光板打光在面上, 另一個方是就擋去白衫的光,將EV比例相差2EV內.可用 PARTIAL ND-FILTER (COKIN 有).
(3) 同一個POST影兩張相(一張主體測光,一張白衫測光值再MINUS 1至1.5EV ), DIGTIAL執相咪得.