Ok, I'm confused.

I really don't understand shutter speed and video. In photography, the shutter speed relates to the amount of time that the sensor is exposed to light. In video though, the shutter is being constantly exposed, so how does shutter speed even fit in? For the 5DII, the framerate is always 30fps.

Someone please un-confuse me.

The sensor isn't being constantly exposed to light. It's being read constantly (thirty times a second). The shutter speed therefore cannot drop below 1/30th, but can go as high as the camera will allow.

so if you are in video mode and you set the shutter to 1/15, it's really shooting at 1/30?

Is that why there's a problem with rolling shutter?

It would be impossible to shoot 1/15 at 30 fps. You couldn't take 30 1/15 second exposures in a second, if that makes sense.

This has nothing to do with the rolling shutter issue, which instead has to do with how information is read from the sensor. (top to bottom)

Okay so rolling shutter problem is caused by slowness of read data from top to bottom of the sensor. Correct?

Future Man wrote:
Ok, I'm confused.

I really don't understand shutter speed and video. In photography, the shutter speed relates to the amount of time that the sensor is exposed to light. In video though, the shutter is being constantly exposed, so how does shutter speed even fit in? For the 5DII, the framerate is always 30fps.

Someone please un-confuse me.

30fps = frame rate.

The frame rate is how many individual frames are being taken from the sensor. The minimum shutter speed with 30fps video is 1/30sec, but can be anything faster than that.

With CCD and CMOS sensors, they are in fact constantly exposed to light, BUT, their images are frequently being offloaded to the image processor. So, the image sensor is exposed to light for a period of time (the shutter speed) and the data it gathers is moved to the processor and then it repeats the process.

Me_XMan wrote:
Okay so rolling shutter problem is caused by slowness of read data from top to bottom of the sensor. Correct?

Rolling shutter effects are artifacts caused by picture conditions changing between when the shutter opens and when it closes. Sort of like motion blur for really fast objects.

So, shooting video at 1/200 would result in a less "blurry" sequence than video shot at 1/30th right? In other words, the ladder would have more motion blur to it I assume. Is this correct?

rcheliphotog wrote:
It would be impossible to shoot 1/15 at 30 fps. (top to bottom)

Actually, it is possible. I shoot 1/15 and 1/7.5 on with a 720p 60fps camera for effect or to compensate for computer flicker/roll. It can also be switched to record 30fps and utilizes the same shutter speeds.

Chris Sharp wrote:
So, shooting video at 1/200 would result in a less "blurry" sequence than video shot at 1/30th right? In other words, the ladder would have more motion blur to it I assume. Is this correct?

Not sure what you mean by the ladder, but yes, shooting at 1/200 will introduce less motion blur. However, where motion blur is shunned in photography, it's practically necessary in filmography. The motion blur gives you the sense of smooth motion in movies. When the shutter speed is too high, everything looks stilted and jittery (think of the D-Day sequence in Saving Private Ryan). You'll have to experiment with shutter speed and focal length to get the right mix.

jfulton wrote:
Actually, it is possible. I shoot 1/15 and 1/7.5 on with a 720p 60fps camera for effect or to compensate for computer flicker/roll. It can also be switched to record 30fps and utilizes the same shutter speeds.


You aren't shooting 30 frames per second with a shutter speed of 1/15 second/frame, because video cameras record in real-time, meaning that 1 second of footage corresponds to 1 second of time elapsing. To get an exposure of 1/15 sec per frame, you'll need 2 seconds of time: 1/15 seconds/frame * 30 frames = 2 seconds of time.

Now, I know that my camcorder can record at a frame rate of 1/15sec, but it records at 15fps (actually, it still records at 30fps, but it doubles each frame so that during playback, it only shows 15 unique frames per second). It can also utilize a shutter of 1/10sec, but it records at 10fps.

Daniel Bates wrote:
The sensor isn't being constantly exposed to light. It's being read constantly (thirty times a second). The shutter speed therefore cannot drop below 1/30th, but can go as high as the camera will allow.

Shhhh! Don't tell my 5D2 !

Me_XMan wrote:
Okay so rolling shutter problem is caused by slowness of read data from top to bottom of the sensor. Correct?

Yes, basically. The effect of a rolling shutter in video is very similar to the slit formed by first and second curtain of a focal plane shutter to enable fast shutter speeds. If you have a very fast moving subject traveling perpendicular to the shutter travel (such as the rotor blades below) the position of the subject will be recorded differently for different parts of the image, which can lead to some interesting though mainly undesirable results.

For digital video, the effect results from serially reading individual pixel rows instead of reading the complete sensor content at once.

(sample courtesy of wikipedia)

So what is the most commonly, or recommended shutter speeds for 1080 24fps and 720 60fps?