1/30 shutter and 1/60 shutter in 60i and 30p modes

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filmguy123

Veteran
Film shoots at 180 degree shutter by default, which is 1/60 of a second at 30p or 1/48 at 24p... so when you shoot 1/30 at 30p mode, is that the same as having a film shutter (almost) at 360 degrees? It seems that would create a lot of blur; how come I seem to have very little extra blur when I drop the shutter to 1/30 in 30p mode to get some more light?


Also, in 60i at 1/60, does this mean that every field is only exposed for 1/120 of second? Wouldn't this give even less blur? Is this what makes video look more video-esque? Does dropping the shutter to 1/30 in 60i mode make the motion look more like 1/60 in 30p mode? Why or why not?


Just need some help wrapping my head around that!! Thanks!
 
Yes you'll have a ton more blur at 1/30 than at 1/60th. Look for it, it's there.

And no, the fields aren't exposed at 1/120, they're exposed at 1/60.

You cannot expose 1/30 in 60i mode, it's not possible. You can't hold the shutter open longer than the frame rate. When you select a shutter that's slower than the frame rate, the system has to go into "frame accumulation" mode, where it actually blends multiple frames together and writes them out multiple times. So 24p at 1/24 = 24 frames per second, but 24p at 1/6 = 6 frames per second, each one a combination of four frames all blended together and all repeated on the tape or card.

If you shoot 60i at 1/30, you'll find that your vertical resolution has dropped in half because only one field is used.
 
Exposing 60 fields (a field happens 1/60 of a second) for 1/60 of a second, wouldn't that be the same as a 360 degree shutter on a camera though? How does that work without introducing a ton of blur?
 
The blur comes from the amount of motion that happens in any particular exposure. 1/60th is not overly blurry. 1/60th is actually crisper than 1/48th, the "film standard".
 
Right, I get that. But 1/60 at 30p, that is 180 degrees shutter per frame, or exposure of half the time the frame is shot, right? So 1/60 at 60p would be exposing for the entire duration of the frame, or a 360 degree shutter, right? Woudln't that, on the same shot with the same motion, introduce twice the motion blur?

So, with 60i, that is 60 fields, wouldn't each field be exposed for 360 degree time then? Unless each field was captured at 1/120, which would make each whole frame 1/60?
 
filmguy123 said:
Right, I get that. But 1/60 at 30p, that is 180 degrees shutter per frame, or exposure of half the time the frame is shot, right? So 1/60 at 60p would be exposing for the entire duration of the frame, or a 360 degree shutter, right? Woudln't that, on the same shot with the same motion, introduce twice the motion blur?
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No, because there's not more motion per frame. You're getting twice as many images per second, but each is equally crisp.

So, with 60i, that is 60 fields, wouldn't each field be exposed for 360 degree time then? Unless each field was captured at 1/120, which would make each whole frame 1/60?
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You're overthinking it. At 1/120 you'll get strobier motion.

Whether it's classified as 360 degrees or not, the fact remains that a shot at 1/60th is going to be as blurry or non-blurry as any other shot at 1/60th.
 
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