Can Bang Trang - Ky Thuat Nhiep Anh

8/3/2019 Can Bang Trang - Ky Thuat Nhiep Anh

1/12

Cn bng trng

Nh ta bit, mu sc ca s vt th khng thay i nhng bn thn n li chu nh

hng ca tnh cht ngun sng ni mt trng (ca ngun sng hoc s phn x lit nhng vt th chung quanh).

V d: quang cnh trong nh vo thi im ban sng vi nh sng tri th s cho sc ti sng, nhng khi v ti, ta thp sng cn phng bng n neon (hoc n bngdy tc) th sc ca cnh quang s ng theo mu n.

Cng v l do , khi chp nh mu trng ca chic o trong nh sng ngy s th hinra mu trng ( ng nh n l mu trng). Nhng n s ng mu vng ( nh mu chico c) nu c chp di nh sng ca bng n dy tc, hoc c mu trng xanhnu chp di nh sng n neeon. y chnh l s mt cn bng v mu trn nh

chp ( hnh 37a).Cn bng trng (white balance) l mt thut ng ch n chc nng loi b s mtcn bng v mu ( color cast) trn nh chp. Ta s cho my nh bit c tnh chtngun sng ni mi trng chp nh. Qua , my nh t hiu chnh b phn cmquang nhn nh chnh xc hn phn t no c mu trng v phn t no c muen, ng thi c s phn bit tt hn gia cc i tng.

Hnh 37 cho ta mt v d v s mt cn bng mu. Hnh a v b c chp vo thiim sng sm. Nhng hnh a cchp vi ch khng ci t cn bng mu nntng mu nh chp nh ng sang sc xanh ca nh sng ban mai. Ta thy mu catm p phch trn tng khng cn gi c sc m hn, cnh ca v cc chi tit

khc cng vy, u ph mt mu xanh dng nht. Trong khi , mu xanh dng catm p phch (pha ngoi) th nh c tip sc trng m hn ln.

hnh 37b, ch cn bng nh sng trng loi b nh snh xanh ca mi trng tr li tng mu sng ti hn (khng b tng mu xanh nh hng). Cc s vtdng nh ly li c s khc bit mu sc c hu ca chng. Chnh s xc nhng tng mu ca tng chi tit ( tht s l , xanh tht s l xanh, ) v s khcbit mu gia chng mt cch trung thc lm cho bc nh trng sinh ng vxc thchn.

S xc nh ng tng mu cho bc nh rt quan trng. N l mt s quan trng trong

ngh thut nhip nh.


2/12

(37a) Tng mu bc nh ng sang muxanh dng ca nh sng ban sm.

(37b) nh c s cn bng ng, ph hp.Mu sc trung thcgip bc nh trngsinh ng hn.

Hnh 37: Cn bng trng


3/12

nh sng tt nht chp nh l nh sng trng (ca bui sng hay nh sng trngca n flash) . Cc loi nh sng khc th t nhiu u c s nh hng v tng munh chp.

Qu trnh cn bng trng l gip my xc nh tnh cht ngun sng ni mi trng. T, mu sc khi thu nhn s c lc b nhng sc d tha. N cho php iuchnh v nh li tng mu ca bc nh, hn ch nhng nh hng ca ngun sngmi trng. Nu cnh chp c nh sng nng hoc lnh, th my nh cn iu tit phhp bc nh khng qu xanh hoc qu mu cam. V vy m nhng ch th mutrng s trng sng hn, v mu tng th ca tm hnh tr nn chn thc hn.

ph hp vi tng tnh hung, my nh c lp trnh sn mt s ch tngng vi tnh cht ca nh sng. C th k ra mt s loi m chng ta thng gp nhnh sng ban ngy, nh sng hunh quang, nh sng c my, nh sng Vonfram ( nbng), nh sng n flash, Nu chng ta s dng mynh trong mi trng no thchn ch WB ph hp vi mi trng y, my nh lc s hot ng theo s cit .

Di y l mt s ch cn bng trng thng c cc hng sn xut quan tmv lp trnh sn trong my:

(a) Auto/Fine:k hiu (AUTO)trong ch ny, my nh t ng thch ng vimu sc t nhin m khng quan tm nngun sng.


4/12

(b) Daylight/Sunnyday: k hiuthch hp khi s dng chp ngoi tri(khng my). Nu bn thch tng mu sngm th c th s dng ch ny trongnh di nh sng n neson.

(c) Cloundy:K hiu S dng khitri c my hoc ni c nh sng u m mm nh khi tri y my.


5/12

(d) Incandescent light/ tungsten light: K

hiu .y l ch khi ta chp nhdi nh sng vng ca n bng dy tc.

(e) Fluorescent:n hunh quang cphn thnh nhiu loi ty theo hng snxut.

Bng n neon s dng trong gia nhBng n neon loi bn

Bng n neon s dng trong cng s vnphng.


6/12

(f) F lash:nh sng trng ca n flash rttt gip loi b mt cn bng mu vto cho tm nh c tng mu trung thc.Tuy nhin tm bao ph n flash nh km

trong my compact cn nhiu hn ch. Mts my nh compact c chn cho phps dng km v flash ngoi.

Hnh 38: Cc ch cn bng trng.

1. Chng ta nhc nhiu v mu sc ca ngun sng, bit ngun sng mu g sgip t WB ngon.Vy lm thno xc nh mu ngun sng chnh xc? Thang nhit mu theo Kelvin c dngcho vic ny. Di y l mt sloi ngun sng ph thng v nhit mu tng ng:

mu nh La dim => 1700 K (Match flame)

mu nh Nn, n du => 1850 K (Candle flame, oil lamps)
http://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/CandleLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/MatchLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/CandleLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/MatchLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/CandleLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/MatchLight.jpg


7/12

mu lc Tri t msng, n Tungsten yu => 2000K

mu nh n (n si t) => 27003300 K (Incandescent light bulb)

mu nh n Studio => 3350 K-3400K (Studio "CP"light,Studio lamps, photofloods..)

mu nh Trng, nh n xenon arc => 4100 K Moonlight, xenon arc lamp

mu nh sng hong hn & bnh minh => 5000 K (Horizon daylight)

mu nh sng ban ngy bt, n flash nh thng => 55006000 K (Typical daylight, electronic flash)mu lc Tri trong,c nng => 6000K (Bright sunshine with clear sky)mu lc Tri sng, c my => 6500 K Daylight, overcastmu lc Tri nng nhiu my => 7000K (Slightly overcast sky)mu lc Tri sng trng => 8000K (Hazy sky)
http://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/HorizonLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/XenonArcLamp.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/PhotoFloods250.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Incandescent.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/TungstenLight2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/HorizonLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/XenonArcLamp.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/PhotoFloods250.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Incandescent.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/TungstenLight2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/HorizonLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/XenonArcLamp.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/PhotoFloods250.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Incandescent.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/TungstenLight2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/HorizonLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/XenonArcLamp.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/PhotoFloods250.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Incandescent.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/TungstenLight2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/HorizonLight.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/XenonArcLamp.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/PhotoFloods250.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Incandescent.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/TungstenLight2.jpg


8/12

mu lc Tri nng to, lc c my => 9000K (Open shade on clear day ) mu Mn hnh CRT (TV, my tnh) => 9300 K CRT screenmu lc Tri nng, trong xanh => 11,000K (Sunless blue skies )mu Trn vng ni, tri nng to, lc c my => 20,000+K (Open shade in mountains on a really clearday)

- Thnht: khi chp xc nh mnh ang trong mi trng nh sng no, t t nhit mu khchnh xc chkhng chn thun l 5,6 ci mode My/Nng/n tup/n m my c sn.

Cch t WB bng tay trn my Canon:

Cn trn my Nikon th d ly:
http://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/SetCustomWBNikon2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/SetCustomWB2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/SetCustomWBNikon2.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/SetCustomWB2.jpg


9/12

- Thhai: Mun nh c tng mu "lnh" i => gim nhit mu, mun nh c tng mu "m" ln =>tng nhit muV d:

PS: Cc clu , ci v gia gim nhit mu ny n cng ging tra gia v khi nu n, nhiu qu khngc, t qu khng c, va lm thay i cht xu tng mu ca nh mi l ngon

lancelot sa : 29-10-2009 lc 10:31

Lm quen vi cn bng trng

Nhiu ngi khng quan tm ti cn bng trng trn my nh, nhng yu t ny li nh hng trc tipti cht lng bc hnh.

Bn cn iu chnh cn bng trng (White Balance - WB) v khi , mu sc ca nh tht hn. minhha r hn cho cn bng trng, bn c th chp mt cnh vt vo hai thi im khc nhau trong ngy. Rrng, tng mu ca hai nh khc nhau, mc d nhn bng mt thng, khung cnh khng c g khc bit.

Nguyn nhn l my nh tip cn vi nhng ngun sng khc nhau. V d, di nh sng n hunhquang th nh s mang tng mu xanh nht. vi nh sng n si t, n vonfram, nh s c tng muvng.

Mu sc ca bc nh di cc ngun sng khc nhau. nh: Digital Photography School.

iu chnh cn bng trng

Trc ht, cn tm hiu v nhit mu. Nhit mu c n v l Kelvin ( K). Mu en ng vinhit mu l 0 K. Khi ni n nhit mu ca vt ngha l ni ti sng ca vt , ch khng

phi nhit ca n.

* Xem bng nhit mu Kelvin trong cc iu kin nh sng khc nhau.

Trong iu kin ngoi tri, mt tri v iu kin kh hu (my, sng m, bi) c th lm tng hocgim nhit mu. Trong nh, nhit mu thay i theo bng n, in p, loi ht sng.
http://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_1.aspxhttp://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_1.aspxhttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Figure1.jpghttp://i16.photobucket.com/albums/b5/aidungbeokhong/ViduLinhtinh/Figure1.jpghttp://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_1.aspx


10/12

Bn cnh , my nh cng cung cp mt s ch d dng iu chnh cho my.

* Mt s thit lp c bn thng thy trn my nh.

Mc d ch t ng cn bng trng ca my nh hin nay u tt, nhng khng phi lc no ncng chnh xc. Nhiu ngi vn thch thit lp thng s cn bng trng th cng trong mt s trng

hp, mu sc ca bc nh c chnh xc nht. Mo thng hay c s dng l dng mt t giytrng t trong mi trng nh sng m bn mun, chp th vi kiu vi cc thng s khc nhau ti khi

bc nh cho mu trng ca t giy l chun nht. Lu gi li thit lp ny v bt u chp bnh thng.Trong v d di y, bc hnh u tin s dng ch t ng cn bng trng chp trong nh di nhsng n si t - mu sc ca bc nh c v m v hi ng vng so vi thc t. Bc nh th hai cho musc "tht" vi cc thit lp cn bng trng sau khi ngi cm my s dng mo trn.

Khi ch t ng.
http://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_2.aspxhttp://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_2.aspxhttp://sohoa.vnexpress.net/SH/Camera/2009/09/3B9B0DE6/page_2.aspx


11/12

Sau khi s dng thit lp cn bng trng th cng. nh: Digital Photography School.

S dng cn bng trng nh mt cng c sng to.

Khng phi tt c nhip nh gia u mun mu sc ca bc hnh phi tht chnh xc. Vi cc thit lp bnt ng hay K khc nhau ca cn bng trng, ngi chp c th thoi mi sng to cho ra nhngsn phm ngh thut ng . Trong v d di y, nhit K khc nhau to cm gic khc nhau ngixem.

Bng hoa - chp vi ch cn bng trng t ng.


12/12

Khi thay i nhit mu ln 2800 K.

Nu nhit mu l 10.000 K. nh: Digital Photography School.

Trich : Tun Hng

Suu tam/Trich 1 so ky thuat nhiep anh

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Can Bang Trang - Ky Thuat Nhiep Anh