Shutter speed in video?

[ckhorne]

I need help understanding a concept. I've only used video a couple times on my 5D2 - mostly for the novelty of it. I understand that ISO is the equivalent to using more sensitive film or bumping up the gain, and that aperture works exactly the same.

However, what I don't understand is how shutter speed translates to video on a dslr. Obviously, the shutter doesn't actually move while taking pictures, yet when I change the shutter speed and keep ISO and aperture constant, the video gets lighter or darker accordingly.

How is the shutter speed factored in? Is it only a mathematical representation of the exposure? Does it actually make a difference in the sampling of the image off the sensor?

Please enlighten me...

[richwig83]

http://www.youtube.com/watch?v=5kJKqin73Wo

[ckhorne]

Ok- that shows the different effects, but how is it actually accomplished in the camera / software?

[RWatkins]

Originally Posted by ckhorne

Ok- that shows the different effects, but how is it actually accomplished in the camera / software?

This might help.
http://blog.planet5d.com/anh




Also, the CMOS sensor used in the 5D MK II is a rolling shutter.
http://en.wikipedia.org/wiki/Rolling_shutter
http://www.dvxuser.com/jason/CMOS-CCD/



Or, are you asking how the sensors 'see' the image, since there are 21 million pixels and only 2.1 million pixels in the video made. The answer from Canon is they use binning to achieve this
http://www.ccd.com/ccd103.html

[aroundlsu]

Originally Posted by ckhorne

Ok- that shows the different effects, but how is it actually accomplished in the camera / software?

Without having to understand the technology behind it, just accept it is an electronic shutter. All video cameras have electronic shutters and they are effective at reducing light. No trickery involved.

Now, if you want your video to look like film you have to keep the shutter at double the frame rate. That means for 30p video you want to shoot at 1/60. For 24p footage shoot at 1/48 (or 1/50 on a dslr). If you go higher it will start to look choppy. Go lower and it will start looking mushy.

[bsaber]

I've been wondering this myself lately.

[Mark II]

Originally Posted by aroundlsu

Without having to understand the technology behind it, just accept it is an electronic shutter. All video cameras have electronic shutters and they are effective at reducing light. No trickery involved.

Now, if you want your video to look like film you have to keep the shutter at double the frame rate. That means for 30p video you want to shoot at 1/60. For 24p footage shoot at 1/48 (or 1/50 on a dslr). If you go higher it will start to look choppy. Go lower and it will start looking mushy.

Does the 1/50 apply towards fast moving subjects? Such as Surfing .... or does one need A faster SS?

[Thalagyrt]

Originally Posted by Mark II

Does the 1/50 apply towards fast moving subjects? Such as Surfing .... or does one need A faster SS?

You're not trying to freeze action with video - higher shutter speeds will make the video look artificial/choppy whereas shooting at 1/50 will look natural/smooth because each frame carries motion blur to and from the previous/next frames.

[aroundlsu]

Originally Posted by Thalagyrt

You're not trying to freeze action with video - higher shutter speeds will make the video look artificial/choppy whereas shooting at 1/50 will look natural/smooth because each frame carries motion blur to and from the previous/next frames.

Right. And the great thing about video is you can pan/track moving subjects. So I person running around a track can still look sharp if you just follow him smoothly with a tripod.

[Fahad79]

good question!

from what i've read.. the combination of the shutter speed with the frames per second results in mimicking the shape a movie film camera's shutter. The types of shutters are explained here:

http://en.wikipedia.org/wiki/Shutter...amera_shutters

Basically what you get with 24fps video and exactly 1/48 shutter speed is the shape of traditional movie film camera shutters (which ever one it is). In some video dslrs you can't get exactly 1/48 so you're stuck with 1/50. The general consensus being that it's good enough.

Also, from what i've read, making the "shape" of the shutter with this combination can reduce the jello effect.

So it's basically a combination of tradition and technical workaround.

cheers.

[bsaber]

^Thanks for the explanation!

[Fahad79]

no problem... i know a lot of theory, not so much practice :<

[Mike]

I was wondering this myself, thanks for the thread!

[harcosparky]

I watched a video from this guy about shooting HD video on the 7D.

I was unhappy with the video results until I saw some of these videos.

My camera settings ....

Manual Mode - 30 fps =
Shutter = 1/60 shutter speed
ISO 160/320/640 <--- use one of these ONLY
Aperture - I adjust aperture to get proper exposure.

Watch this guys video ..... ( he talks about some adjustments you make in camera setup )
http://www.youtube.com/watch?v=62wx5S0jHCk

Watch what he says about LENS SELECTION --- this might surprise you!!!!
http://www.youtube.com/watch?v=XLR93g4Hd2s

[carshop]

Good stuff there.