What's the use of a physical shutter any more?

[Noel_Carboni]

Having read Rob Galbraith's review of the Canon EOS-1D Mark III, and the emergence of the new live view feature (which, by the way, was also available in the Canon EOS-20Da astro dSLR), one has to wonder: What's the real need for a physical shutter any more?

Okay, so the mirror directs most of the light to the viewfinder, and some of the light to the AF and metering sensors, and when it swings away ALL of the light goes to the sensor. This is a Good Thing. We probably do want to keep the swing-away mirror (though this could possibly even be revisited in less than top-of-the-line models with sensors doing ISO 6400 and beyond).

I suppose the shutter protects the sensor from accumulating dirt.

One could imagine doing away with the physical shutter mechanism, and maybe replacing it with a nice clear pane of (easily cleanable) protective glass.

A subtle difference may be that turning the chip on and off is probably virtually instantaneous across the entire chip, while very short physical shutter times involve the opening and closing curtains following each other across the field of view, exposing only a slit. Does anyone actually rely on this for specific effects? I've not heard of this. And even if so, one could imagine a slightly more sophisticated electronic chip enable/disable control that could work the same magic.

Is the physical shutter - no doubt an expensive component to make, and one that wears out and causes trouble - possibly doomed? Am I missing something important the shutter does for us?

By the way, I had an Olympus digital camera in 1999, a C-2500L, that worked much like what I'm describing here. It did not have interchangeable lenses, and so imager dirt accumulation wasn't a big issue.

-Noel

[James_Van_Artsdalen]

See Charge-coupled device - Wikipedia, the free encyclopedia about Interline transfer devices.

It's not just Q.E. (Quantum Efficiency, or the sensitivity or ISO capability) that's important as that link suggests. You'd like to have as much as dynamic range as possible and more junk in each photosensor counts against dynamic range.

I don't know if Canon has said how Live Preview is implemented. It may just be that they accept a lot of smearing knowing it can't be seen in the real world, or is so minor nobody cares. Or perhaps the sensor supports a very high speed read-out mode, and Canon treats it as an Interline sensor with exposed transfer lines.

When price is more important than image quality, such as Point & Shoot, shutters go away. When dynamic range and image quality matter and the price point permits, such as SLR, you wind up with mechanical shutters. Mechanical shutters are solved a problem from R&D in the film days, so they aren't uneconomic or risky solutions to use.

[michaelnotar]

i could see things going the way of being like a video camera, where the SLR offers video on the back for some period of time, (which would be increased as technology advances) from which many separate images could be captured. without a traditional shutter, the FPS rate would be really high...

problem is how do you do not have a shutter and still make it SLR. seems it would work by composing on the back screen like crappy P/Ss or perhaps a rangefinder system.

even with an electronic shutter you speak of, i dont think getting rid of it would happen. it would be nice if it stored up and only came down when changing lenses.

the shutter actually isnt too bad to replace, about $450 parts + labor for the FF canons and thats after 100k+ shots as specs say, probably it can go much longer...but canon has to garentee a certain minimal number of shots not a maximum.

with your olympus was it the only camera with the technology? was it soon abandoned? how was the electronic shutter technology recieved by the public/photographic community?

[Noel_Carboni]

I need to be clear here... I'm proposing the possibility of an SLR which retains the reflex mirror but has no physical shutter.

James makes a good point about image quality, but from what I'm reading I don't see anything in the review that says the image quality of the 1D Mark III when used in Live View mode suffers. Perhaps for the actual shot they close the shutter then take the shot in a normal way with shutter opening then closing again during Live View mode, I don't know.

I'm sure my Oly C-2500L wasn't the only camera with electronic shutter, but it may be one of the few that have had through the lens optical viewfinding and an electronic shutter combination. Operationally, it drove like an SLR. I do know that they had several earlier models that did that as well around 1997... The D500L and the D600L.

Even at $450 parts/labor, that's $450 more than a camera with no physical shutter to wear out. I'm thinking this could be a way to make the low-end models less expensive to manufacture, and thus more price competitive.

-Noel

[Martin_Doudoroff]

Originally Posted by Noel_Carboni

Perhaps for the actual shot they close the shutter then take the shot in a normal way with shutter opening then closing again during Live View mode, I don't know.

That's my understanding. When you actually take a shot, the shutter closes, the CMOS chip is reset, and then a proper exposure is taken.

Here's a short video clip that shows Live View in action. The Live View is clearly interrupted when the shot is taken.

Notably, you can also reel off shots with the mirror locked up and live view turned off. The advantage of this feature is simply that the camera is pretty quiet (because the mirror is flopping up and down.)

[Phil_Taylor]

Don't Nikon digital cameras do the exposure timing electronically after certain faster shutter speeds are reached?

Perhaps the answer would be to have a 'capping shutter' like in a medium format camera such as the Hasselblad, which allows lens changes without light getting to the film plane past the lowered mirror. In the case of a digital camera it would keep the dust out.

The capping shutter could be a much more crude device, and therefore cheaper to make. If we got rid of the focal plane shutter, we could get rid of restricted speeds for flash synch? OK, someone will tell me about high speed mode on the gun, I know, I know.

[JohnSievert]

My sense is that as TFT's improve that we will eventually see an "ESLR" - electronic viewfinder camera with interchangeable lenses. Right now, the TFT's are not that good - very grainy and the rube goldberg contraption of a mirror and shutter is still required.

J