Electronic Front-Curtain Shutter

[Abitconfused]

What does Electronic Front-Curtain Shutter do?

[Manfred M]

Electronic is simply the type of shutter mechanism you have; this is universal in modern higher end cameras. Camera phones and point & shoot camera use purely electronic shutters, i.e. no shutter blades at all. Traditional SLR shutters were mechanically timed.

Front curtain describes the timing of the firing of the electronic flash. When shooting at or below your camera's synch speed, the shutter fully opens and as soon as it opens, the shutter fires; this is front curtain (in Nikon speak, also known as first curtain in Canon speak). The alternative is rear curtain (or second curtain), where shutter is fully opened and the flash fires just before the shutter closes.

These techniques come into play when the photographer "drags the shutter", i.e. shoots at shutter speeds considerably slower than synch speed with flash. Ambient light is recorded and the flash then freezes the action. The front curtain and rear curtain give you totally different looking images.



This is a front curtain shot as the car is frozen by the flash, but the shutter is still open as the vehicle moved forward after the flash has fired and the beam of the headlights stretches out, but the car itself is not visible.

[Abitconfused]

OK. Please explain, I thought ambient light did not include flash but incident light did.

[george013]

I think something else is mentioned.

http://nps.nikonimaging.com/technica...ctronic_front/

I don't exactly understand what's written.

George

This one is clearer.
https://sony-paa-pa-en-web--paa.cust...er-function%3F

George

[Mike Buckley]

The front curtain and rear curtain give you totally different looking images.

I understand that is true when photographing a moving object. Is it also true when nothing in the scene is moving?

[DanK]

if you google 'rear-curtain flash' without the quotes, you will find lots of explanations of the difference.

[Manfred M]

I understand that is true when photographing a moving object. Is it also true when nothing in the scene is moving?

You are correct - no movement means both front curtain and rear curtain will give you identical results.

[Manfred M]

OK. Please explain, I thought ambient light did not include flash but incident light did.

Your camera does not care what the light source is. If you set up your exposure appropriately you can get a scene that uses both flash AND ambient light. This is exactly what happens when a photographer uses fill flash - the bulk of the scene is lit by ambient light, but the flash is used to open up shadows on the subject.

My incident (flash) light meter gives me the readings of the contribution of incident and flash hitting the subject as a percentage that each contributes to the scene.

[revi]

I think the "Electronic" here is important.
There is indeed the flash sync option with front or rear curtain, as Manfred explained, but there's also the option
(on some camera's) to have the start of the exposition through an electronic shutter. (not sure how to explain this better)

I can hear the difference on my camera, "electronic front curtain" is quieter, which is useful in some situations.
The links George posted above are relevant to this.

[dje]

What does Electronic Front-Curtain Shutter do?

The Sony article referenced by George explains it pretty well.

Mechanical rolling focal plane shutters achieve fast shutter speeds by having the second curtain start closing before the first one has fully opened so you have this moving exposure slit. Curtain speed is typically about 1/250 sec.

With electronic first curtain, instead of using the mechanical first curtain, an electronic reset is appiled to all rows of pixels and then this is removed row by row down the sensor at a rate the same as the speed of the mechanical curtains. With the second curtain mechanical, data readout from the sensor can occur following the closure of the curtain. However for an electronic second curtain to be used, data readout would have to be fast enough to be done at the rate of the curtain speed. My understanding is that this is generally beyond the capabilities of current technology.

Dave

[DanK]

I think this may vary with manufacturer. My little Lumix LX-100 has only one electronic-shutter mode, as far as I can tell, and it is fully electronic. If you set it to use the electronic shutter using the main menus, the shutter still has a click, which made me think that it was the half-electronic shutter described above, but when I explored further, I had a hunch that the noise was artificial, because there is a second menu that changes the shutter mode, and with that one, the camera is silent. I checked the advanced manual, which is available only online, and it confirms that the shutter sound is electronic when the electronic shutter is selected.

[george013]

The Sony article referenced by George explains it pretty well.

Mechanical rolling focal plane shutters achieve fast shutter speeds by having the second curtain start closing before the first one has fully opened so you have this moving exposure slit. Curtain speed is typically about 1/250 sec.

With electronic first curtain, instead of using the mechanical first curtain, an electronic reset is appiled to all rows of pixels and then this is removed row by row down the sensor at a rate the same as the speed of the mechanical curtains. With the second curtain mechanical, data readout from the sensor can occur following the closure of the curtain. However for an electronic second curtain to be used, data readout would have to be fast enough to be done at the rate of the curtain speed. My understanding is that this is generally beyond the capabilities of current technology.

Dave

Just some thoughts I can't find an answer on. The start position of the curtains must be different with a electronic or mechanic front curtain. Electronic must start with an open front curtain, mechanic both curtains are closed.

George

[Manfred M]

Just some thoughts I can't find an answer on. The start position of the curtains must be different with a electronic or mechanic front curtain. Electronic must start with an open front curtain, mechanic both curtains are closed.

George

George - this is how mirrorless cameras and DSLRs in LiveView work. The shutter is out of the way (i.e. open) so that light can hit the sensor, and the shutter cycles when the shutter release is pressed. When I change lenses on my mirrorless camera, I get to see the sensor, every time I do this.

[george013]

That's what I meant. The start position must be different. It's not clearly mentioned in the different video's or animations.

George

[Didace]

George - this is how mirrorless cameras and DSLRs in LiveView work. The shutter is out of the way (i.e. open) so that light can hit the sensor, and the shutter cycles when the shutter release is pressed. When I change lenses on my mirrorless camera, I get to see the sensor, every time I do this.

On my Sony a6000 I can choose to have the electronic front curtain shutter on or off.

[george013]

On my Sony a6000 I can choose to have the electronic front curtain shutter on or off.

I think you hear a click when switching between them.

George

[Manfred M]

That's what I meant. The start position must be different. It's not clearly mentioned in the different video's or animations.

George

I find that the camera manufacturer's literature and website content is probably handled by the marketing departments and that tends to mean that the information given always has that marketing direction.

The other part that is confusing is that there is no consistent terminology used by the various manufacturers. All modern camera shutters are "electronic" in some sense as they no longer use mechanical gear trains to control the shutter timing. Camera phones or point & shoot cameras use this electronic polling and call that an electronic shutter and do so without the benefit of a mechanical shutter at all.

[george013]

I find that the camera manufacturer's literature and website content is probably handled by the marketing departments and that tends to mean that the information given always has that marketing direction.

The other part that is confusing is that there is no consistent terminology used by the various manufacturers. All modern camera shutters are "electronic" in some sense as they no longer use mechanical gear trains to control the shutter timing. Camera phones or point & shoot cameras use this electronic polling and call that an electronic shutter and do so without the benefit of a mechanical shutter at all.

But now it's about an electronic front-curtain shutter. There's still a mechanical rear or second curtain left.

George

[Manfred M]

But now it's about an electronic front-curtain shutter. There's still a mechanical rear or second curtain left.

George

Whatever the heck that is. Sounds like a half shutter design where the sensor data is cleared and the camera starts recording data and after some period a mechanical shutter closes. Being a mirrorless Sony, I can see how / why they would go this way - it's a simpler (i.e. less expensive to manufacture) design and should be more reliable (although fully mechanical focal plane shutters have been around for a very long time and are quite reliable).

[dje]

I think this may vary with manufacturer. My little Lumix LX-100 has only one electronic-shutter mode, as far as I can tell, and it is fully electronic. If you set it to use the electronic shutter using the main menus, the shutter still has a click, which made me think that it was the half-electronic shutter described above, but when I explored further, I had a hunch that the noise was artificial, because there is a second menu that changes the shutter mode, and with that one, the camera is silent. I checked the advanced manual, which is available only online, and it confirms that the shutter sound is electronic when the electronic shutter is selected.

Dan I don't know the details of the LX100 shutter. A lot of compact non-interchangable lens cameras use a mechanical leaf shutter rather than a two curtain focal plane shutter. The LX100 may be a focal plane shutter though and if so you may find the curtain speed to be quite low in fully electronic mode. A downside of low curtain speed is low flash sync speed and possible distortion of images with subject movement. Panasonic seem to be leading the way to some extent with the introduction of fully electronic shutters.

Dave