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shutters & apertures?

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July 7, 2005 7:44:48 PM

Archived from groups: rec.photo.digital.zlr (More info?)

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

More about : shutters apertures

Anonymous
July 8, 2005 3:23:43 AM

Archived from groups: rec.photo.digital.zlr (More info?)

"Bob" <bogus@dingbat.net> 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: mrmnews@the-meissners.org
http://www.the-meissners.org
Anonymous
July 8, 2005 10:28:12 AM

Archived from groups: rec.photo.digital.zlr (More info?)

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
Anonymous
July 8, 2005 12:35:16 PM

Archived from groups: rec.photo.digital.zlr (More info?)

Michael Meissner <mrmnews@the-meissners.org> writes:

>> 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.

> 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).

I don't know about the FZ5, but Canon Powershot G-series cameras
have a traditional mechanical shutter (of the central shutter
type).

My impression is that a mechanical shutter is quite common in higher
end ZLR digital cameras.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
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