Shutter on m4/3 cameras - how it work?

Started Oct 1, 2012 | Discussions
linux99 Senior Member • Posts: 1,112
Shutter on m4/3 cameras - how it work?

So on my SLR like cameras the shutter is two cloth (or occasionally metal) curtains which whoosh past the sensor with a small open slit open on them to define the time of the exposure. As you reduce the time of the exposure the gap between the two curtains gets smaller.

In the composition phase the curtains are closed - the mirror is down and protects the sensor.

Anyone know how a m4/3 camera manages exposure time? AFAIK the sensor is always exposed - no curtain or mirror covering it. So how does exposure work with m4/3 cameras?

Before the flaming starts - I'm asking out of genuine curiosity / ignorance. I don't have view on the superiority of either system.

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grapher
grapher Senior Member • Posts: 1,090
Re: Shutter on m4/3 cameras - how it work?

You push the button, and the shutter closes. The camera erases the sensor. From now on it operates the same as a DSLR. When the pic is finished, the shutter opens again to enable liveview.

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Andy Crowe Senior Member • Posts: 1,587
Slow motion video of the G1 shutter in action

Here's a slow motion video of the G1 shutter in action.

http://www.youtube.com/watch?v=-dK6Qa1Iy4Y

Basically during the "composition phase" the sensor is exposed and in live-view mode.

When the shutter button is pressed the shutter actually closes, the sensor is wiped, then the shutter reopens using the slit technique that SLRs use. Once the image is read off the sensor the shutter opens again and enters live-view mode again.

Now this is true of most m4/3 models, but it is possible to avoid having to close the shutter before taking a picture by wiping lines just a head of the shutter closing (which creates a kind of virtual slit). Cameras like the NEX7 can do this and it will probably come to all mirrorless cameras sooner or later.

So on my SLR like cameras the shutter is two cloth (or occasionally metal) curtains which whoosh past the sensor with a small open slit open on them to define the time of the exposure. As you reduce the time of the exposure the gap between the two curtains gets smaller.

In the composition phase the curtains are closed - the mirror is down and protects the sensor.

Anyone know how a m4/3 camera manages exposure time? AFAIK the sensor is always exposed - no curtain or mirror covering it. So how does exposure work with m4/3 cameras?

Before the flaming starts - I'm asking out of genuine curiosity / ignorance. I don't have view on the superiority of either system.

John Bean (UK) Forum Pro • Posts: 18,035
Re: Slow motion video of the G1 shutter in action

Andy Crowe wrote:

Now this is true of most m4/3 models, but it is possible to avoid having to close the shutter before taking a picture by wiping lines just a head of the shutter closing (which creates a kind of virtual slit). Cameras like the NEX7 can do this and it will probably come to all mirrorless cameras sooner or later.

The NEX "electronic first curtain" works really well, completely removing the "shutter shock" effect, reducing lag and making the whole operation quieter as well. It probably helps shutter life too.

It's the only thing I miss since selling my NEX-5N to help fund my E-M5 purchase; the E-M5 shutter noise is already so much more refined than the NEX I can only image how quiet it would be if it also had an electronic first curtain - and no more problems with 1/100 sec shutter speeds with some lenses.

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OP linux99 Senior Member • Posts: 1,112
Re: Shutter on m4/3 cameras - how it work?

Thanks to all who answered.

The film clip is fascinating.

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