Ｐａｇｅ 139010 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 通常モードに戻る ┃ ＩＮＤＥＸ ┃ ≪前へ │ 次へ≫ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ▼About Focal length sandralong 2010/01/22(金) 19:35 ─────────────────────────────────────── ■題名 ： About Focal length ■名前 ： sandralong <zandralongue@gmail.com> ■日付 ： 2010/01/22(金) 19:35 ■Ｗｅｂ ： http://www.piqalle.com -------------------------------------------------------------------------
| Let痴 start by imagining your lens is a projector in fact it is exactly that: it projects an image of the scene onto your camera痴 sensor. It bundles the light from the scene into the lens, then sends it to the sensor: there is a point in the path of light where the image appears to come from like the light fanning out of a film or transparency projector. This point goes by various technical names such as rear vertex or rear principal point, but the key thing is that we measure focal length from that point. Now, we set up the lens to focus on a very distant subject (said to be 殿t infinity because the light rays are for all purposes parallel to each other) and measure from the point from which the image appears to be projected in a straight line to the plane in which the sharp image lies typically, that痴 a shade below the physical surface of the sensor. The point from which the image is projected can lie within the lens we壇 expect that. But this definition reveals the odd thing that the point from which the image is projected can also lie behind the lens and even in front. Look at a typical modern telephoto lens: its marked focal length is 300mm, but its physical length could be as short as 120mm or less. Similarly, you池e sure to have noticed that a wide-angle lens or focal length setting of 24mm is way longer than 24mm. Even the space between the rear of the lens to the sensor is greater than 24mm. <a href=http://foro-computacion.webcindario.com/index.php?topic=1393.new#new>article link</a> - <a href=http://www.symmetry-us.com/katachi/forum/index.php?topic=8140.new#new>article link</a> - <a href=http://cpm-cm.com/webboard/index.php?topic=1432.new#new>article link</a> - <a href=http://cpm-cm.com/webboard/index.php?topic=1433.new#new>article link</a> - <a href=http://cpm-cm.com/webboard/index.php?topic=1434.new#new>article link</a> - <a href=http://cpm-cm.com/webboard/index.php?topic=1435.new#new>article link</a> - <a href=http://www.fairtaxusa.net/forum/viewtopic.php?f=2&t=30526>article link</a> - <a href=http://www.fairtaxusa.net/forum/viewtopic.php?f=2&t=30527>article link</a> - <a href=http://www.fairtaxusa.net/forum/viewtopic.php?f=2&t=30528>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=4&t=4289>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=4&t=4290>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=5&t=4291>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=6&t=4292>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=7&t=4293>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=8&t=4294>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=9&t=4295>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=20&t=4296>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=20&t=4297>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=18&t=4298>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=18&t=4299>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=40&t=4300>article link</a> - <a href=http://thexxxbase.com/Forum/viewtopic.php?f=40&t=4301>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=1&t=7000>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=7&t=7001>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=3&t=7002>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=4&t=7003>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=6&t=7004>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=5&t=7005>article link</a> - <a href=http://www.floridahomebrew.com/forums/viewtopic.php?f=5&t=7006>article link</a> - <a href=http://xc.shrapnet.com/forums/viewtopic.php?f=2&t=81013>article link</a> - <a href=http://xc.shrapnet.com/forums/viewtopic.php?f=2&t=81015>article link</a> - <a href=http://xc.shrapnet.com/forums/viewtopic.php?f=2&t=81016>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20915.new#new>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20916.new#new>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20917.new#new>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20919.new#new>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20920.new#new>article link</a> - <a href=http://indave.com/SMFcommunity/index.php?topic=20922.new#new>article link</a> - <a href=http://askchristianwomen.com/forum/viewtopic.php?f=2&t=15285>article link</a> - <a href=http://askchristianwomen.com/forum/viewtopic.php?f=2&t=15286>article link</a> - <a href=http://askchristianwomen.com/forum/viewtopic.php?f=2&t=15287>article link</a> - <a href=http://www.exhibitionhost.com/forums/viewtopic.php?f=2&t=47218>article link</a> - <a href=http://www.exhibitionhost.com/forums/viewtopic.php?f=2&t=47219>article link</a> - <a href=http://www.exhibitionhost.com/forums/viewtopic.php?f=2&t=47220>article link</a> - <a href=http://www.hathor.ch/forum/viewtopic.php?f=2&t=65772>article link</a> - <a href=http://www.hathor.ch/forum/viewtopic.php?f=2&t=65773>article link</a> - <a href=http://www.hathor.ch/forum/viewtopic.php?f=2&t=65774>article link</a> - <a href=http://chinesebridge.info/bbs/viewtopic.php?f=2&t=6063>article link</a> - <a href=http://chinesebridge.info/bbs/viewtopic.php?f=2&t=6064>article link</a> - <a href=http://chinesebridge.info/bbs/viewtopic.php?f=2&t=6065>article link</a> - <a href=http://www.edogs.ru/modules.php?name=Forums&file=viewtopic&p=11670#11670>article link</a> |