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shutters & apertures?
Hi Group,
I just bought a new Panasonic FZ5, and I was wondering if digital cameras still have apertures and shutters, as the owners manual still refers to them. I've heard that the click we hear when we push the button is just there to reassure us that something is really happening but has nothing to do with the exposure itself. Considering what can be done these days with electronics, it seems that shutters and apertures would be a thing of the past. Done electronically, there would be no need for slow shutter speed or narrow depth of field. Unless it was desired for effect. Or is there still a limit to how fast the sensor can process light? Is there a resource somewhere that explains how a digital camera captures and processes light? Any ideas will be appreciated. Bob |
#2
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"Bob" writes:
Hi Group, I just bought a new Panasonic FZ5, and I was wondering if digital cameras still have apertures and shutters, as the owners manual still refers to them. I've heard that the click we hear when we push the button is just there to reassure us that something is really happening but has nothing to do with the exposure itself. Considering what can be done these days with electronics, it seems that shutters and apertures would be a thing of the past. Done electronically, there would be no need for slow shutter speed or narrow depth of field. Unless it was desired for effect. Or is there still a limit to how fast the sensor can process light? Is there a resource somewhere that explains how a digital camera captures and processes light? Any ideas will be appreciated. The shutter on a point & shoot or prosumer camera is an electronic shutter (ie, sensor is cleared, and then at the end of the shutter cycle, the sensor is read). They also don't have the traditional mirror, so yes the sound you hear when the shutter is pressed is a recording played to give you comfort, and on some/many cameras can be turned off. DSLRs by and large use the traditional two curtain shutter SLRs used (the Nikon D70 does use a combination two curtain shutter and electronic shutter to achieve the 1/500 sync speed). The aperture is the same as in film cameras (ie, a set of circular blades closing/opening to admit a given amount of light). Depth of field depends on the physics of light and the given aperture & sensor size. However, most digital cameras have a smaller sensor than film cameras, so you get more apperent depth of field. Here is an article that explains digital cameras: http://electronics.howstuffworks.com/digital-camera.htm -- Michael Meissner email: http://www.the-meissners.org |
#3
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Michael Meissner wrote:
[] The shutter on a point & shoot or prosumer camera is an electronic shutter (ie, sensor is cleared, and then at the end of the shutter cycle, the sensor is read). They also don't have the traditional mirror, so yes the sound you hear when the shutter is pressed is a recording played to give you comfort, and on some/many cameras can be turned off. Many traditional cameras also do not have a mirror, it's only the SLR style which does. I must admit that I can't stand the artificial sounds which are programmed - you immediately loose the benefit of silent operation! Some ZLR cameras also need a mechanism for stopping light getting to the sensor while the sensor is still operating (e.g. for dark frame subtraction). I'm not sure if they have a separate mechanical shutter in the lens for this, or can simply close the aperture diaphragm blades right down. Cheers, David |
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