Mechanical Shutters?

[mkrupp]

Here's a question for all you electronic engineers out there; why do we need mechanical shutters on digital cameras?  Couldn't it all be done electronically?

[mkrupp]

So is this a really good (difficult) question or a really stupid (obvious) one and I'm just missing it?

If camera designers can get away from the mechanical shutter and do it all in electronics then it would seem to me that many new possibilities would open up. For instance; if we can take an exposure of 1/1,000 of a second than perhaps, with fast enough memory, we could take 1,000 exposures in a second. If we didn't have mirrors flapping around and shutter blades whipping back and forth the factors limiting the number of exposures would be in the electronics and in the world of electronics 1/1,000 of a second is kinda slow.

Mitch

[mahleu]

Because you need to look out through the lens using the mirror. Although this can be avoided using a pelicle mirror.

[mkrupp]

Well ... that's why we need a mirror, but why do we need the shutter? If we are using a film camera then it's obvious, the shutter controls the length of time the light exposes the film for. With a sensor could it not simply be turned on, or sampled, for the length of time we need to make the correct exposure once the mirror is out of the way?

I'm all for speculation and without really knowing for sure that's all anyone here can do. So here are a couple of my guesses, from most to least likely;

1) It's comes down to money. The design of mechanical shutters has pretty much been perfected and the factories that build them are already in place and can pump them out relatively cheaply. The engineering and design of sensors and the electronics needed to replace shutters would not come cheap, so why bother.

2) Digital is so new they haven't had the time to perfect it yet.

3) It can't be done.

4) They haven't thought of it yet and I'm the first one to come up with the idea. Thank you, thank you very much.

5) Everyone loves a shutter. Who in their right mind would buy a camera without one? I like been a shutterbug, but a sensorbug?  And what would happen to places like Lens and Shutter? Lens and Sensor! Not likely.

6) Kodak has a vested interested in shutters and just won't let go.

7) How else would we keep the dust (and our fingers) off our sensors? The temptation would be too great, seeing it peaking out from behind the mirror every time we changed a lens! Poke, poke. Yep, looks good to go. Pokie, poke.

The cultural changes required would be too great as we would no longer be able to say "shutter speed" and we would get confused.

Mitch

[usathyan]

So is this a really good (difficult) question or a really stupid (obvious) one and I'm just missing it?

If camera designers can get away from the mechanical shutter and do it all in electronics then it would seem to me that many new possibilities would open up. For instance; if we can take an exposure of 1/1,000 of a second than perhaps, with fast enough memory, we could take 1,000 exposures in a second. If we didn't have mirrors flapping around and shutter blades whipping back and forth the factors limiting the number of exposures would be in the electronics and in the world of electronics 1/1,000 of a second is kinda slow.

Mitch
[a href=\"index.php?act=findpost&pid=126750\"][{POST_SNAPBACK}][/a]

Just my thoughts though - i know that the real high end professional models all have mechanical shutters...and the lower end pro-sumer ones have digital/hybrid shutters...(a quick hint is to check the highest flash sync speed and you will know if your camera has a mechanical or digital).

So, anyways - i think the reason is that mechanical shutters have been (a) time tested and ( reliable and © accurate. Only time will tell if the digital shutters are really that good - I think the next generation shutters will start incorporating them or will start deploying hybrid ones (both a mechanical as well as digital)

Well, i may be wrong..just my 2 cents anyways.

[Morgan_Moore]

Here's a question for all you electronic engineers out there; why do we need mechanical shutters on digital cameras?  Couldn't it all be done electronically?
[a href=\"index.php?act=findpost&pid=126329\"][{POST_SNAPBACK}][/a]

I find the concept of mechanical shutters frustrating

I have tried making a shutterless camera using my eyelike back (!)

my research at the time made told me (basically)

to get a good low noise digital file you interpolate the shot (image data) with a 'black reference' image allowing noise to be cancelled out somehow

the black refeerence needed to be recorded near the time of the exposure as the temp of the chip etc

hence the need for dark in front of the sensor and therefore the need for a shutter !

That is my simple understanding

S

[Jack Varney]

It seems to me that the problem with the technology, as we have it now, is that the sensor cannot be turned on and off.

1. It must be turned on to begin the exposure. This would be equivalent to opening the shutter, so, no problem.

2. At exposure's end the sensor cannot be merely turned off. The pixel wells must be read and digitized. This takes time and while the some pixel sites are being read and digitized others will be changing as motion and illumination in the scene  changes. Loss of resolution. movement like ghosts and other aberations will most certainly result.

3. If it were practical to read all of the pixel sites in parallel it might work. However, to read and digitize tens of millions of pixels in parallel would likely take a camera that would require a cart to move it!