Différences entre les versions de « Photographie/Filtres optiques/Filtres gris neutre »

 
== L'obtention de temps de pose très longs ==
 
Les temps de pose très longs permettent d'obtenir de très beaux effets de flou sur les éléments mobiles d'une scène, tandis que les éléments fixes demeurent parfaitement nets. De telles prises de vues sont très faciles à obtenir au crépuscule ou en pleine nuit mais presque impossibles en plein jour sans accessoires particuliers : en effet, le niveau de lumière est alors presque toujours trop élevé, de sorte que même en réglant la sensibilité sur la valeur minimale et en fermant le diaphragme à fond, on n'arrive pas à obtenir des temps de pose suffisamment longs.
 
 
Là encore un filtre de densité relativement élevée, 1 ou 2, permet d'obtenir sans problème les temps de pose de plusieurs secondes nécessaires à ce genre de prise de vues. Faut-il préciser que l'usage d'un [[trépied]] très rigide s'impose, sauf bien sûr si l'appareil peut ou doit être parfaitement immobilisé d'une autre manière, comme c'est le cas pour la photographie prise depuis la voiture.
 
===Calcul du temps de pose avec des filtres===
{| class="wikitable"
| | <center>'''Tps de pose (s) sans filtre (ou avec un filtre polarisant uniquement)'''</center>
| | <center>'''Tps de pose (s) avec un ND8'''</center>
| | <center>'''Tps de pose (s) avec un ND16'''</center>
| | <center>'''Tps de pose (s) avec un ND8+ND16'''</center>
| | <center>'''Tps de pose (s) avec un ND400'''</center>
| | <center>'''Tps de pose (s) avec un ND1000'''</center>
| | <center>'''Tps de pose (s) avec un ND400+ND16'''</center>
| | <center>'''Tps de pose (s) avec un ND1000 + un ND16'''</center>
| | <center>'''Tps de pose (s) avec un ND400+ND16+ND8'''</center>
| | <center>'''Tps de pose avec un ND1000 + un ND16 + un ND8'''</center>
| | <center>'''Tps de pose (min) avec un ND1000 + un ND400'''</center>
 
|-
| | <center>1/1000</center>
| | <center>1/125</center>
| | <center>1/60</center>
| | <center>1/8</center>
| | <center>1/2,5</center>
| | <center>1</center>
| | <center>6</center>
| | <center>16</center>
| | <center>51</center>
| | <center>2 min 8 sec</center>
| | <center>6 min 40 sec</center>
 
|-
| | <center>1/800</center>
| | <center>1/100</center>
| | <center>1/50</center>
| | <center>1/6</center>
| | <center>1/2</center>
| | <center>1,3</center>
| | <center>8</center>
| | <center>20</center>
| | <center>1 min 4 sec</center>
| | <center>2 min 40 sec</center>
| | <center>8 min 20 sec</center>
 
|-
| | <center>1/640</center>
| | <center>1/80</center>
| | <center>1/40</center>
| | <center>1/5</center>
| | <center>1/1,6</center>
| | <center>1,6</center>
| | <center>10</center>
| | <center>25</center>
| | <center>1 min 20 sec</center>
| | <center>3 min 20 sec</center>
| | <center>10 min 25 sec</center>
 
|-
| | <center>1/500</center>
| | <center>1/60</center>
| | <center>1/30</center>
| | <center>1/4</center>
| | <center>1/1,25</center>
| | <center>2</center>
| | <center>12</center>
| | <center>32</center>
| | <center>1 min 42 sec</center>
| | <center>4 min 16 sec</center>
| | <center>13 min 20 sec</center>
 
|-
| | <center>1/400</center>
| | <center>1/50</center>
| | <center>1/25</center>
| | <center>1/3</center>
| | <center>1</center>
| | <center>2,5</center>
| | <center>16</center>
| | <center>40</center>
| | <center>2 min 8 sec</center>
| | <center>5 min 20 sec</center>
| | <center>16 min 40 sec</center>
 
|-
| | <center>1/320</center>
| | <center>1/40</center>
| | <center>1/20</center>
| | <center>1/2,5</center>
| | <center>1,25</center>
| | <center>3</center>
| | <center>20</center>
| | <center>50</center>
| | <center>2 min 40 sec</center>
| | <center>6 min 40 sec</center>
| | <center>20 min 50 sec</center>
 
|-
| | <center>1/250</center>
| | <center>1/30</center>
| | <center>1/15</center>
| | <center>1/2</center>
| | <center>1,6</center>
| | <center>4</center>
| | <center>25</center>
| | <center>1 min 4 sec</center>
| | <center>3 min 24 sec</center>
| | <center>8 min 32 sec</center>
| | <center>26 min 40 sec</center>
 
|-
| | <center>1/200</center>
| | <center>1/25</center>
| | <center>1/13</center>
| | <center>1/1,6</center>
| | <center>2</center>
| | <center>5</center>
| | <center>32</center>
| | <center>1 min 20 sec</center>
| | <center>4 min 16 sec</center>
| | <center>10 min 40 sec</center>
| | <center>33 min 20 sec</center>
 
|-
| | <center>1/160</center>
| | <center>1/20</center>
| | <center>1/10</center>
| | <center>1/1,3</center>
| | <center>2,5</center>
| | <center>6</center>
| | <center>40</center>
| | <center>1 min 40 sec</center>
| | <center>5 min 20 sec</center>
| | <center>13 min 20 sec</center>
| | <center>41 min 40 sec</center>
 
|-
| | <center>1/125</center>
| | <center>1/15</center>
| | <center>1/8</center>
| | <center>1</center>
| | <center>3,2</center>
| | <center>8</center>
| | <center>50</center>
| | <center>2 min 8 sec</center>
| | <center>6 min 50 sec</center>
| | <center>17 min 4 sec</center>
| | <center>53 min 20 sec</center>
 
|-
| | <center>1/100</center>
| | <center>1/12</center>
| | <center>1/6</center>
| | <center>1,3</center>
| | <center>4</center>
| | <center>10</center>
| | <center>1 min 4 sec</center>
| | <center>2 min 40 sec</center>
| | <center>8 min 32 sec</center>
| | <center>21 min 20 sec</center>
| | <center>1 h 6 min 40 sec</center>
 
|-
| | <center>1/80</center>
| | <center>1/10</center>
| | <center>1/5</center>
| | <center>1,6</center>
| | <center>5</center>
| | <center>13</center>
| | <center>1 min 20 sec</center>
| | <center>3 min 20 sec</center>
| | <center>10 min 40 sec</center>
| | <center>26 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/60</center>
| | <center>1/8</center>
| | <center>1/4</center>
| | <center>2</center>
| | <center>7</center>
| | <center>17</center>
| | <center>1 min 46 sec</center>
| | <center>4 min 26 sec</center>
| | <center>14 min 13 sec</center>
| | <center>35 min 33 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/50</center>
| | <center>1/6</center>
| | <center>1/3</center>
| | <center>2,5</center>
| | <center>8</center>
| | <center>20</center>
| | <center>2 min 8 sec</center>
| | <center>5 min 20 sec</center>
| | <center>17 min 4 sec</center>
| | <center>42 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/40</center>
| | <center>1/5</center>
| | <center>1/2,5</center>
| | <center>3</center>
| | <center>10</center>
| | <center>25</center>
| | <center>2 min 40 sec</center>
| | <center>6 min 40 sec</center>
| | <center>21 min 20 sec</center>
| | <center>53 min 20 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/30</center>
| | <center>1/4</center>
| | <center>1/2</center>
| | <center>4</center>
| | <center>13</center>
| | <center>33</center>
| | <center>3 min 33 sec</center>
| | <center>8 min 53 sec</center>
| | <center>28 min 26 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/25</center>
| | <center>1/3</center>
| | <center>1/1,6</center>
| | <center>5</center>
| | <center>16</center>
| | <center>40</center>
| | <center>4 min 16 sec</center>
| | <center>10 min 40 sec</center>
| | <center>34 min 8 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/20</center>
| | <center>1/2,5</center>
| | <center>1/1,3</center>
| | <center>6</center>
| | <center>20</center>
| | <center>50</center>
| | <center>5 min 20 sec</center>
| | <center>13 min 20 sec</center>
| | <center>42 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/15</center>
| | <center>1/2</center>
| | <center>1</center>
| | <center>9</center>
| | <center>27</center>
| | <center>1 min 7 sec</center>
| | <center>7 min 6 sec</center>
| | <center>17 min 46 sec</center>
| | <center>56 min 53 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/13</center>
| | <center>1/1,6</center>
| | <center>1,2</center>
| | <center>10</center>
| | <center>31</center>
| | <center>1 min 17 sec</center>
| | <center>8 min 12 sec</center>
| | <center>20 min 30 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/10</center>
| | <center>1/1,3</center>
| | <center>1,6</center>
| | <center>13</center>
| | <center>40</center>
| | <center>1 min 40 sec</center>
| | <center>10 min 40 sec</center>
| | <center>26 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/8</center>
| | <center>1</center>
| | <center>2</center>
| | <center>16</center>
| | <center>50</center>
| | <center>2 min 4 sec</center>
| | <center>13 min 20 sec</center>
| | <center>33 min 20 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/6</center>
| | <center>1,3</center>
| | <center>2,7</center>
| | <center>20</center>
| | <center>1 min 7 sec</center>
| | <center>2 min 46 sec</center>
| | <center>17 min 47 sec</center>
| | <center>44 min 26 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/5</center>
| | <center>1,6</center>
| | <center>3</center>
| | <center>26</center>
| | <center>1 min 20 sec</center>
| | <center>3 min 20 sec</center>
| | <center>21 min 20 sec</center>
| | <center>53 min 20 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/4</center>
| | <center>2</center>
| | <center>4</center>
| | <center>32</center>
| | <center>1 min 40 sec</center>
| | <center>4 min 10 sec</center>
| | <center>26 min 40 sec</center>
| | <center>1 h 6 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/3</center>
| | <center>2,7</center>
| | <center>5</center>
| | <center>43</center>
| | <center>2 min 13 sec</center>
| | <center>5 min 33 sec</center>
| | <center>35 min 33 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/2,5</center>
| | <center>3,2</center>
| | <center>6</center>
| | <center>51</center>
| | <center>2 min 40 sec</center>
| | <center>6 min 40 sec</center>
| | <center>42 min 40 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/2</center>
| | <center>4</center>
| | <center>8</center>
| | <center>1 min 4 sec</center>
| | <center>3 min 20 sec</center>
| | <center>8 min 20 sec</center>
| | <center>53 min 20 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/1,6</center>
| | <center>5</center>
| | <center>10</center>
| | <center>1 min 20 sec</center>
| | <center>4 min 10 sec</center>
| | <center>10 min 25 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
 
|-
| | <center>1/1,3</center>
| | <center>6</center>
| | <center>12</center>
| | <center>1 min 38 sec</center>
| | <center>5 min 8 sec</center>
| | <center>12 min 49 sec</center>
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
| style="background-color:#cccccc;border:0.05pt solid #000000;padding:0.049cm;"|
|}
 
== L'obtention d'une faible profondeur de champ ==