All LUMIX G cameras offer a choice of mechanical and electronic shutter modes to give photographers an added degree of flexibility in the way they take their pictures. In many cases there is little practical difference between the two modes, and most people wouldn’t really notice which was in action or know which would be best for the situation. However, when we became a little more advanced in our photography it pays to appreciate what these two ways of shooting have to offer – and their limitations.
Mechanical shutter is on by default in all Lumix G models. You will know that mechanical shutter is in operation because you will hear the clicks of the shutter working as you take your pictures. As the shutter button is pressed a metal gate passes across the sensor to block it and then expose it again so the light from the lens can strike the imaging sensor. When the exposure is finished the gate closes again – before returning to its resting position out of sight. That’s why we hear two clicks when we take a picture – one at the beginning of the exposure and one at the end.
When the shutter fully is open between the clicks the whole sensor is exposed to the light coming in through the lens, and the picture is recorded.
As rows 1 and 2 record their image the flicker of the light might be on the bright part of its cycle, but when rows 3 and 4 come to shoot the cycle might be on its dark phase. If this is repeated as the sensor records in sequence down the rows of pixels the picture will appear with bright and dark bands, according to which part of the cycle the light source was at when those pixel rows recorded the image.
In the main menu of your camera you will find an option for ‘Shutter Type’ – often near the end of the Camera menu. Here you will find options for MSHTR (mechanical shutter) and ESHTR (electronic shutter). There will sometimes be an Auto mode, and even EFC – I shall come on to EFC later.
When the electronic shutter is selected the metal gate doesn’t move to start or end the exposure when the shutter button is pressed – the sensor just starts reading the light striking it immediately. So, there is no audible noise and nothing moves in the camera body.
So, what is the practical difference
The great thing about electronic shutter mode is that it is silent, which allows us to take pictures without disturbing those around us and without drawing attention to ourselves. With electronic shutter we also avoid vibrations during while the picture is being taken that may occur when a shutter blade moves to start the exposure.
The electronic shutter mode is suitable for most kinds of photography, but because of the way the sensor sends information to the camera’s processor it doesn’t produce good results when used in fluorescent lighting or under light sources that flicker. Using the electronic shutter in these conditions leads to horizontal bands of different brightness levels on the picture. This happens because the rows of pixels don’t all report at the same time, so in effect different horizontal bands of the frame are taking their part of the picture at different times. As fluorescent light flickers, sometimes it is bright and in the next fraction of a second it is dark. We don’t notice this so much with our eyes (until the fluorescent tube gets old) but the sensor will notice, and will produce an image in which some areas of the frame have been exposed to less light than others – just because the light is flicking.
The result is a series of bands of different brightnesses down the picture. This is called ‘banding’, and it rarely looks attractive, creative or as though it was done purposefully.
If we are photographing something that’s moving quickly across the frame it might appear distorted if we shoot using the electronic shutter mode. If your shutter speed is very short the distortion will probably not make an appearance, but when the shutter is open for longer periods the top of the subject could be recorded significantly before the bottom. If a man on a bike is traveling from right to left in the frame, for example, his head might be recorded in the top right of the picture but his feet in the bottom left – making his form stretch diagonally across the picture.
I’ve used a spinning coin to demonstrate the effect on an object that is principally in the same place in the frame, but which has become buckled by the time delay between the top and bottom of the disc being recorded by the sensor. You can see that in mechanical shutter mode the coin appears perfectly circular because the whole frame is recorded at the same moment.
The degree of rolling shutter you incur will be a product of the speed at which your camera’s sensor reads out, which is often a factor of the speed of the camera’s processor. In general, older models incur more rolling shutter.
Electronic First Curtain
Some newer camera models offer a shutter mode called Electronic First Curtain, or EFC. When this mode is selected the exposure starts in electronic shutter mode, but ends with the passing of a physical shutter – as in mechanical shutter mode. The idea of this mode is that we avoid the dangers of vibrations caused by the first passing of the physical curtain at the beginning of the exposure. Ending the exposure with a physical curtain allows us to also avoid rolling shutter and banding from flickering light sources.
Pros and Cons of each shutter option
Electronic First Curtain
Some shooting modes will select the type of shutter in use automatically for you. If you select High Resolution mode in the G9, for example, the camera automatically switches to electronic shutter to avoid internal vibrations shaking the camera and destroying the resolution you are trying to make the most of. Post Focus/Focus Stacking modes and 4K Photo also use electronic shutter. If you have electronic shutter selected you will note that flash menu modes will be shown in grey and will be un-selectable.
Silent mode allows you to get really close to people without them realising you are taking a picture
While Silent shooting mode does use the electronic shutter, it does a little more than just that. If you usually have the audio shutter and AF confirmation bleeps on Silent mode will switch them off, and it will also disable the autofocus assist light. The audio from video clips will be muted. None of these things will happen if you just select electronic shutter – only in Silent mode.