{"id":1523,"date":"2017-02-27T08:02:46","date_gmt":"2017-02-27T03:02:46","guid":{"rendered":"http:\/\/cgauthier.ca\/en\/?p=1523"},"modified":"2017-03-11T08:11:44","modified_gmt":"2017-03-11T03:11:44","slug":"composition-depth-of-field","status":"publish","type":"post","link":"https:\/\/blog.cgauthier.ca\/en\/2017\/02\/27\/composition-depth-of-field\/","title":{"rendered":"Composition et depth of field"},"content":{"rendered":"

Principe de r\u00e9ciprocit\u00e9, \u00e9quilibre entre l’ouverture du diaphragme, la vitesse de l’obturateur et la sensibilit\u00e9 du capteur (d\u00e9not\u00e9 sur l’\u00e9chelle ISO)<\/em><\/p><\/div>\n

L’ouverture du diaphragme se calcule en f-stop, qui est une valeur relative. C’est le ration entre la longueur focale de l\u2019objectif et de diam\u00e8tre de l\u2019ouverture du diaphragme.<\/p>\n

Un nombre f-stop plus grand laisse entrer moins de lumi\u00e8re<\/p>\n

Un objectif lumineux est plus recherch\u00e9, f\/1.2 f\/1.4<\/p>\n

Les objectifs poss\u00e8dent une \u00e9chelle standard qui correspond a une croissance \u00e0 la racine carr\u00e9e de 2 :<\/p>\n

Ouverture du diaphragme d’un objectif, d’une ouverture maximale ( f \/ 1.8 ou plus grand) et minimale (f \/ 22 ou plus petit)<\/em><\/p><\/div>\n

(ouvert) f\/1, f\/1.4, f\/2, f\/2.8, f\/4, f\/5.6, f\/8, f\/11, f\/16, f\/22, f\/32 (ferm\u00e9)<\/p>\n

Chaque calibration correspond au double de la lumi\u00e8re du pr\u00e9c\u00e8dent<\/p>\n

Pour fin de r\u00e9ciprocit\u00e9, l\u2019ouverture, la vitesse de l\u2019obturateur et la sensitivit\u00e9 du film sont inter-reli\u00e9s : doubler l\u2019ouverture, ou doubler la vitesse ou doubler la sensitivit\u00e9 du capteur donne une luminosit\u00e9 constante.<\/p>\n

 <\/p>\n

Diaphragme ferm\u00e9<\/p><\/div>\n

 <\/p>\n

Diaphragme ouvert<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

Diaphragme ferm\u00e9<\/p><\/div>\n

Photo par Nicole Rath<\/a><\/p>\n

Canon EOS 60D
\n1\/25 sec
\nf\/22
\nISO 500<\/p>\n

 <\/p>\n

Diaphragme ouvert<\/p><\/div>\n

1\/4000 sec
\nf\/2
\nISO 500<\/p>\n

Principe de r\u00e9procit\u00e9<\/h4>\n

Vitesse: de 1\/25 \u00e0 1\/4,000: vitesse 7\u00a0fois plus rapide<\/p>\n

Ouverture du diaphragme: \u00a0de f \/22 \u00e0 f \/2: 7 fois<\/p>\n

ISO: constant
\n(ouvert) f\/1, f\/1.4, f\/2, f\/2.8, f\/4, f\/5.6, f\/8, f\/11, f\/16, f\/22, f\/32 (ferm\u00e9)<\/p>\n

 <\/p>\n

Ces valeurs sont influenc\u00e9es principalement par les variables suivantes:
\nDistance entre le sujet (l’avant plan) et la cam\u00e9ra
\nLa longueur focale de la lentille
\nL’ouverture du diaphragme<\/p>\n

 <\/p>\n

 <\/p>\n

Mise au point sur l’avant plan, ouverture du diaphramge maximale<\/p><\/div>\n

Vitesse 1 \/ 3200 sec
\nISO 200
\nF-stop. 2.8
\nLongueur focale 40 mm<\/p>\n

 <\/p>\n

Ouverture maximale du diaphragme pour profondeur de champ\u00a0minimale,<\/p><\/div>\n

Vitesse 1 \/ 3200 sec
\nISO 200
\nF-stop \u00a0f \/ 2.8
\nLongueur focale 40 mm<\/p>\n

 <\/p>\n

Mise au point sur la sculpture, avec diaphragme ferm\u00e9 au minimum<\/p><\/div>\n

Vitesse 1 \/ 40 sec
\nISO 200
\nF-stop \u00a0f \/ 22
\nLongueur focale 40 mm<\/p>\n

 <\/p>\n

Principe de r\u00e9ciprocit\u00e9<\/h4>\n

Image: \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a01 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 2 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a03
\ndiaphramge: \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 f \/ 2.8 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 f \/ 2.8 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0f \/ 22
\nvitesse: \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a01\/3,200 sec \u00a0 \u00a0 \u00a0 1\/3,200 sec \u00a0 \u00a0 \u00a0 \u00a01\/40 sec
\nISO: \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 200 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 200 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 200
\nR\u00e9ciprocit\u00e9: \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a06 fois<\/p>\n","protected":false},"excerpt":{"rendered":"

L’ouverture du diaphragme se calcule en f-stop, qui est une valeur relative. C’est le ration…<\/p>\n","protected":false},"author":3,"featured_media":1357,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[220],"tags":[197],"yoast_head":"\n\n\n\n\n\n\n\n\n\n\n\n\t\n\t\n\n