Dab tsi yog qhov tob ntawm kev yees duab?

2024 Tus sau: Sierra Becker | [email protected]. Kawg hloov kho: 2024-02-26 05:10

Nyob rau hauv lub ntsiab lus ntawm hnub no tsab xov xwm, peb yuav sim qhia ib lub tswv yim raws li qhov tob ntawm teb. Thiab nyob rau hauv cov ntaub ntawv no peb tsis tau tham txog ib tug kab mob, tab sis hais txog qhov tob ntawm lub teb nyob rau hauv kev yees duab. Nws suab zoo li no - qhov tob ntawm qhov chaw.

Txhua tus neeg uas nws cov dej num cuam tshuam nrog thaj chaw no paub zoo txog qhov txhais tau li cas. Tab sis peb, cov neeg siv zoo tib yam, xav nkag siab qee yam. Qhov no muaj tseeb tshwj xeeb rau cov kws yees duab pib.

cov ntaub ntawv dav dav

Ntau ntawm peb tseem tsis tau paub tias txhua tus neeg tau ntsib qhov tob hauv lub neej txhua hnub. Tab sis nws puas ua tau? Cov lus teb yog nyob rau hauv peb lub zeem muag. Ua kom cov lus sib cav no ntseeg tau, nws tsim nyog muab piv txwv yooj yim.

Cia peb pib nrog ib daim ntawv thiab ua ib lub qhov me me rau hauv2 cm diam. Tso nws ntawm koj ob lub qhov muag ntawm qhov deb ntawm 20 cm thiab sim ua kom nws ib txhij pom daim ntawv ntawm nws tus kheej thiab dab tsi nyob hauv lub qhov. Puas tau?! Thiab yog tias tam sim no kaw nws ntawm lwm sab nrog koj txhais tes, ua li cas? Qhov piv txwv yooj yim no piav qhia qhov tob ntawm daim teb.

lus tshaj lij

Peb twb tau paub peb tus kheej nrog qhov tob ntawm qhov chaw - qhov no yog qhov chaw hauv daim duab uas cov ntsiab lus zoo li ntse li sai tau, uas yog, meej, thiab txhua yam yog qhov muag plooj. Nyob rau tib lub sijhawm, nws yuav tsum nkag siab tias qhov tob ntawm kev yees duab yog lub tswv yim zoo nkauj thiab muaj lub siab xav, vim txhua tus neeg muaj lub zeem muag thiab kev nkag siab.

Raws li kev lees paub, koj tuaj yeem xav txog ntau cov duab uas dej nyab hauv Is Taws Nem. Saib ntawm lawv, koj tuaj yeem nkag siab tias txhua tus neeg muaj lawv tus kheej kev nkag siab ntawm cov duab sharpness.

Los ntawm qhov kev xav ntawm kev tshaj lij, es tsis txhob siv lo lus "qhov tob ntawm qhov chaw", nws yog lub npe DOF uas tau siv, uas tau cuam tshuam los ntawm ntau qhov chaw hauv Is Taws Nem lossis cov ntawv xov xwm tshwj xeeb.

Rau txhua tus kws tshaj lij uas nws cov haujlwm cuam tshuam nrog kev tshaj lij kev yees duab, DOF tsis yog lub tswv yim paub daws teeb meem! Cov neeg no pom ntau ntxiv ntawm no - lub cuab yeej muaj zog rau kev tsom mus rau ib qho khoom tshwj xeeb. Nrog nws, koj tuaj yeem tso saib tag nrho ib puag ncig hauv qhov pom tseeb tshaj plaws thoob plaws tag nrho ntawm tus ncej, lossis ua kom pom qhov muag plooj pem hauv ntej lossiskeeb kwm raws li lub tswv yim los yog raws li xav tau.

Tsev kawm sab ntawm qhov tob ntawm qhov chaw hauv kev yees duab

Daim ntawv yooj yim ntawm daim ntawv piv txwv tau tham saum toj no qhia tau hais tias txhua lub koob yees duab ua haujlwm zoo ib yam - ua kom qhov tob ntawm qhov ua rau kom pom tseeb dua. Txwv tsis pub, lub dav hlau focal yuav ua phem heev. Yog tias koj saib ntawm ib qho duab, ces qhov chaw tam sim ntawd (txawm nws yog ib tus neeg, ib qho khoom lossis ib pawg me me ntawm cov khoom) yuav ua kom pom tseeb, thiab txhua yam yuav plooj. Hauv lwm lo lus, peb tsom mus rau qhov ze tshaj plaws rau peb, thiab qhov chaw nyob deb tau saib tsis pom.

Nyob rau hauv lub cuab yeej ntawm ib lub koob yees duab, qhov tob ntawm qhov chaw yog ncaj qha nyob ntawm ob peb yam tseem ceeb:

• lens aperture;
• distance to object;
• focal length.

Hauv cov ntsiab lus yooj yim, qhov tob ntawm thaj chaw yog thaj chaw lossis thaj chaw uas cov khoom raug kaw tau pom nrog qhov tseeb tshaj plaws thiab qhov ntse. Tab sis qhov no muab dab tsi rau peb?

Kev piav qhia

Dab tsi yog qhov tob ntawm kev yees duab rau cov pib tshiab? Aperture yog xam los ntawm cov qauv yooj yim: f / "tus lej". Thiab qhov me me no "tus lej", qhov loj dua lub lens aperture. Yog li ntawd, qhov tob ntawm daim teb yog txo. Tib lub sijhawm, qhov kev ncua deb mus rau ib qho khoom lossis pawg ntawm cov khoom kuj tseem ceeb. Qhov deb lawv nyob, qhov tob ntawm daim teb ntau dua thaum kawg. Yog tias koj muab ob daim duab sib txawvnrug, piv txwv li, cia nws yog 5 meters thiab 50 cm - qhov tob ntawm daim teb nyob rau hauv cov duab yuav txawv heev.

Ib yam lus, yog tias koj teeb tsa hom macro rau ntawm lub koob yees duab-xiav lub thawv thiab thaij duab los ntawm qhov deb ntawm 2-3 centimeters, koj yuav xaus nrog qhov muag plooj, txij li thaj tsam ntawm / u200b\u200b lub sensor ntawm no me me heev.

Tam sim no nws tsim nyog kov ntawm qhov ntev ntawm qhov focal - raws li nws nce, qhov tob ntawm daim teb txo qis. Hauv lwm lo lus, ntawm lub kaum ntse ntse (ua kom pom tseeb luv) qhov tob ntawm daim teb yuav tsuas yog loj, thaum lub kaum me me (ntev tsom xam) qhov tob ntawm thaj teb yuav meager.

Feem ntau, rau kev yees duab portrait, nws yog qhov tseeb ntawm qhov tob tob uas xav tau. Qhov no tso cai rau koj kom paub qhov txawv ntawm cov qauv ntawm qhov chaw nyob, uas tsis tsim nyog saib xyuas. Dab tsi txiav txim siab qhov tob ntawm daim duab hauv cov duab, ntxiv rau cov xwm txheej tau teev tseg?

Aperture tus nqi

Qhov tseeb, lub diaphragm yog lub ntsiab lus tsim lub lens uas tuaj yeem kho lub cheeb ntawm lub qhov uas xa lub teeb mus rau zaj duab xis (hauv cov khoom qub) lossis cov matrix (cov cuab yeej niaj hnub). Hauv lwm lo lus, tus naj npawb ntawm lub teeb dhau los yog hloov kho qhov tseeb ntawm lub diaphragm.

Hauv lus Askiv, lub ntsiab lus no yog hu ua aperture, txawm li cas los xij, hauv kev lees paub dav dav, tsab ntawv Latin F yog siv los qhia txog qib ntawm qhov qhib ntawm qhov aperture., thiab vice versa.

Qhov siab tshaj plaws thiab qhov tsawg kawg nkaus tus nqi aperture yog qhov lojnyob ntawm tus qauv tsim ntawm ib lub lens tshwj xeeb. Feem ntau, ntau lub koob yees duab tuaj nrog lub lens nrog qhov tsawg kawg nkaus aperture tus nqi ntawm f/3.5.

Ntxiv rau qhov tob ntawm qhov chaw hauv kev yees duab, aperture tuaj yeem cuam tshuam qhov nrawm nrawm. Lub teeb ntau lub lens tuaj yeem tso rau hauv, lub sijhawm tsawg lub koob yees duab xav tau kom lub qhov rooj qhib.

Kev cog qoob loo ntawm lub koob yees duab matrix

Nyob rau lub sijhawm uas cov duab thaij tau siv 35mm zaj duab xis, lub tswvyim no tsis muaj nyob. Tus qauv yog ib yam thiab yog li ntawd tsis muaj kev tsis meej pem. Tab sis nrog kev txhim kho ntawm kev vam meej, ntau lub tuam txhab muaj lub sijhawm tshiab rau kev tsim hluav taws xob photosensitive sensors, thiab yuav luag txhua qhov loj me. Yog li pib lub sijhawm ntawm kev yees duab digital.

Tam sim no cov qoob loo tseem ceeb yog qhov taw qhia tseem ceeb uas cuam tshuam rau qhov tob ntawm daim teb hauv cov duab, feem, thiab cov duab zoo. Thiab qhov ntawd txhais tau tias xaiv lub koob yees duab. Lub caij no, cov qoob loo zoo tshaj plaws (cov qoob loo zoo tshaj plaws) yog ze ze rau 35-mm zaj duab xis, vim tias nws yog ib qho tseem ceeb uas qhia qhov txawv ntawm qhov loj ntawm matrix ntawm cov cuab yeej digital thiab cov yeeb yaj kiab ib txwm muaj (35 hli). Muab xam los ntawm qhov sib piv ntawm kab pheeb ces kaum ntawm tus qauv thav duab (43.3 hli) rau kab pheeb ces kaum ntawm ib tug ncej nrog ib tug tsis tiav matrix.

Cov kab pheeb ces kaum ntawm tus ncej yog ib txwm hais ntawm no, txij li cov qoob loo yog raws li qhov ntsuas no. Tab sis txhawm rau txhawm rau pom qhov sib txawv ntawm qhov loj me, koj xav tauqoob loo ntau squared. Piv txwv li, thaj tsam ntawm CANON APS-C sensor (nws qhov kev cog qoob loo yog 1.6) yuav muab sib npaug rau: 1.6 x 1.6=2.56. Nws yog qhov tsawg dua li thaj tsam ntawm tag nrho cov ncej.

Thiab txij li tus ncej tag nrho yog coj los ua lub hauv paus, raws li, tus coefficient tsis tuaj yeem tsawg dua ib qho.

Common False Assumption

Dab tsi yog qhov tob ntawm kev yees duab twb tau hais hauv cov ntsiab lus yooj yim. Tab sis cov kws yees duab pib xav tau kev paub txog kev cog qoob loo. Koj tuaj yeem ua tau raws li qhov kev xav yuam kev tias qhov coefficient no tuaj yeem ua rau kom lub focal ntev ntawm lub lens, uas qhov tseeb tsis tshwm sim. Qhov me me ntawm qhov ntsuas ntsuas tuaj yeem txo lub kaum sab xis ntawm qhov pom ntawm lub lens, yog li txo qhov kev pom ntawm tus ncej. Hauv lwm lo lus, thaum kawg peb tsis muaj dab tsi ntau tshaj li qhov txiav tawm hauv nruab nrab ntawm tag nrho cov ncej.

Thiab coj mus rau hauv tus account qhov tseeb tias cov khoom siv hluav taws xob tau ntsuas cov duab rau ntawm qhov screen thiab nthuav tawm nws, qhov kev xav ntawm kev nce qhov ntev ntawm qhov focal yog tsim. Qhov tseeb, qhov tseeb focal ntev ntawm lub lens yog qhov nws tau siv los ua, thiab ib txwm hais nyob rau hauv kev sib raug zoo rau tag nrho cov ncej.

Scope of application

Qhov qhov tob ntawm qhov zoo tshaj plaws yog xaiv nyob ntawm kev ua haujlwm tua. Ntau tus kws yees duab novice ua qhov yuam kev tshaj plaws - thaij duab nrog lub lens uas nyuam qhuav tau txais nrawm nrog lub siab tshaj plaws aperture. Yog lawm, qee zaum nws yog qhov ncaj ncees, tab sis tsis tas li.

Howkho qhov tob ntawm daim teb hauv daim duab? Thaum thaij duab nrog qhov tob tob ntawm qhov chaw, nws yuav tig tawm tias tsuas yog lub qhov muag yuav nyob rau hauv qhov kev tsom xam, thaum lub taub ntswg yuav plooj. Seb nws yuav tig tawm zoo nkauj raws li qhov tshwm sim yog qhov taw tes moot. Tab sis yog hais tias ib tug neeg lub taub hau yog me ntsis tig mus rau sab, ces lub qhov muag nyob ze yuav pom tseeb, tab sis lub qhov muag nyob deb yuav tawm ntawm qhov chaw ntawm sharpness. Qhov txhaj tshuaj no zoo nkaus li natural.

Vim qhov no, nws tsis tas yuav tsum qhib lub aperture tag nrho, thiab feem ntau nws yog qhov zoo dua los npog nws ob peb nres. Raws li qhov tshwm sim, qhov tob ntawm qhov chaw yuav zoo tshaj plaws, thiab qhov muag plooj yuav nyob rau hauv qhov kev txwv tau txais.

Yog tias koj xav tua ib pab pawg, koj xav tau qhov tob tob ntawm qhov chaw. Ua li no, lub aperture yuav tsum tau them ntau dua - nyob rau hauv thaj tsam ntawm f / 8 txog f / 11 nyob rau hauv zoo sab nraum zoov teeb pom kev zoo.

Hyperfocal nrug (HR)

Muaj lwm lo lus tseem ceeb uas coj los ua ke kev lag luam kev yees duab thiab qhov tob ntawm thaj teb - hyperfocal nrug lossis HF. Qhov kev txhais no yuav tsum tau to taub raws li qhov kev ncua deb ntawm qhov twg, txawm hais tias lub aperture qhib, tag nrho cov khoom thiab cov khoom yuav nrog qhov siab tshaj plaws sharpness. Ntawd yog, qhov no yog tib qhov tob ntawm thaj teb, tab sis nrog kev tsom mus rau infinity.

Nws yog ib qho tseem ceeb uas yuav tsum tau coj mus rau hauv tus account qee cov ntsiab lus:

• Raws li qib ntawm aperture nce, yog li GR.
• Qhov dav ntawm lub lens, qhov me dua GR.

Ultra wide-angle lo ntsiab muag pib ntawm 2-3 meters, uas zoo nkauj ze.

Raws li qhov ntev-ntev lo ntsiab muag muaj kev txhawj xeeb, qhov ntev ntev tshwm sim ntawm no - los ntawm 100 meters lossis ntau dua. Vim li no, shutter speeds thiab wide-angle lo ntsiab muag yog nyiam rau toj roob hauv pes.