I have a Canon EOS R50, a mirrorless camera, which also seems shutterless - If I take pictures of, for example, an airplane with a spinning propeller, will I still get that “strange rubber propeller” effect? 1) the camera may have a shutter and I just don’t recognize it or 2) the sensor is read in such a way as to produce the effect.
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Most consumer cameras use CMOS photo sensors, and among those, only the higher end sensors are capable of global shutter (the image is captured at the same moment electronically). CCD sensors are typically more expensive but h they often use global shutter. The EOS R50 is like most consumer cameras with its CMOS sensor.
Most mechanical shutters will have a leading and trailing curtain with a variable gap between them that controls exposure. The wider the gap, the longer the light hits a row of pixels and the higher the exposure. Your camera’s shutter is slightly different in the fact that instead of using two shutter curtains it only has the trailing one. The exposure is started electronically and stopped mechanically by the trailing curtain. This hybrid shutter is called EFCS (Electronic First Curtain Shutter). Additionally the shutter can be controlled entirely electronically by sampling the sensor values row by row in essentially the same way the mechanical shutter works.
Without a true global shutter, the rolling shutter effect will be produced when filming or photographing fast moving subjects. So yes, your camera would do what most other cameras do.
Thanks. So I am guessing the shutter is only present when actually taking a picture since the view-finder is fed from the sensor?
Yes. If you take a picture and hear the standard click sound that is the mechanical shutter covering the sensor. If you want to shoot silently, that’s when you’d use the electronic shutter. For your camera you can find that setting under the Camera Icon tab in the menu (should be first tab), then the sixth page that starts with focus bracketing. The setting is called shutter mode and will be either Elec. 1st-curtain, or Electronic
The r50 can do electronic shutter or second curtain shutter, but it doesn’t have a global shutter or full mechanical shutter.
So, some ELI5 background on camera sensors. Most sensors read the data from the sensor pixel by pixel, line by line. So what that means is that a small amount of time passes between reading the top lines of the sensor and the bottom lines of the sensor. Most of the time, this doesn’t make much difference. But for fast moving objects (or if you’re panning the camera really fast) it means that the scene can change during that passage of time, which is what gives you trains that lean to one side and propellers that look like they’re made of rubber.
To get around that, you can use a physical shutter. Cameras with “second curtain” shutters physically close off the light to the sensor before they start reading data from the sensor. This means that even though time passes between reading the top and the bottom of the line, the light captured by the sensor does not change during that time, and so the wobbly subjects don’t happen.
A camera with a full mechanical shutter puts a physical shutter at the beginning of the process and the end, but the gains over second curtain only are negligible.
In theory, there is also “global shutter” which is a camera that reads the entire sensor at once, but in practice, this technology doesn’t exist at the consumer mirrorless camera level.
Electronic shutters aren’t all bad though, because they let you do faster shutter speeds than are possible with physical elements, and they let you do higher fps when shooting in burst mode. And electronic shutters are also silent
So with the 2nd type shutter, The sensor is exposed and then the shutter closes, the sensor is read in darkness so the image on it does not change. Then the shutter opens and I start seeing what the camera sees in the view-finder-eyepiece?
Yep!
