Electronic shutter??

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iljitsch Senior Member • Posts: 1,056
Electronic shutter??
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I recently upgraded from the D7100 to the Z fc. With that came something new: the electronic shutter.

You have a choice of three settings:

- electronic first curtain

- mechanical shutter (but not with all lenses???)

- auto: either of the above chosen by the camera (based on what?)

And then you can overrule that by enabling silent shooting. In that case, you can get a fully electronic shutter.

I do know what all of that means:

- mechanical shutter: just like with a DSLR: the actual shutter opens and then closes to expose your photo

- electronic first curtain: with mirrorless, the shutter is normally always open. With this setting, it remains open when you press the shutter button, but the sensor is made ready for the shot electronically and then the shutter closes and the image data is read and the shutter opens again for the viewfinder image

-electronic shutter: nothing mechanical at all, the sensor is cleared electronically and is then read without closing the physical shutter

Except for a limitation or two, it looks like electronic first certain behaves exactly the same as mechanical shutter.

On (D)SLRs, the shutter works using two "curtains". With slow shutter speeds, the first opens, then the shutter stays open for a while, and the second "curtain" closes. Usually both proceed from top to bottom of the image. With short shutter speeds, the second curtain starts to close before the first curtain has completely opened.

The same thing happens with an electronic shutter: perhaps it starts clearing the sensor from top to bottom which takes 1/100 th of a second, but the shutter speed is 1/1000th. So when the electronic "first curtain" is 10% down the sensor, the camera starts reading the data so each pixel has an effective 1/1000 exposure even though it takes 1/100 to read the entire sensor.

So now my question:

It seems the electronic / rolling shutter is super slow! The Z fc supports a flash sync time of 1/200, so it can open the mechanical shutter in 1/400 or less, have the flash go off, and then close the mechanical shutter in 1/400 or less.

But as far as I can tell, a fully electronic shutter, which you get in silent mode, takes more than 1/30 to read. I tested this by showing the camera a 60 frame per second flashing image with a line traveling left to right, and it seems that even at fast shutter times, two full 1/60 frames and then part of a third are recorded by the electronic shutter.

Why could that be? The Z fc can record video at 120 FPS, so you'd think it can read the entire sensor in 1/120.

 iljitsch's gear list:iljitsch's gear list
Nikon D7100 Nikon Z fc Nikon AF-S DX Nikkor 16-85mm f/3.5-5.6G ED VR Nikon AF-S DX Nikkor 35mm F1.8G Nikon AF Nikkor 50mm f/1.8D +7 more
Nikon D7100 Nikon Z fc
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