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Shooting at a higher frame rate

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stan welks
Shooting at a higher frame rate
on Aug 2, 2013 at 7:32:37 pm

If I understand correctly, shooting at a higher frame rate like 60fps:

1. will play back at normal speed in a 30fps or a 24fps Premiere or Final Cut Pro project, is this correct?
2. allows you to slow down footage in post and achieve better quality than footage shot at 24 or 30fps and slowed down?
3. are there reasons to not always shoot at 60fps in case you may want to slow footage down in post?

Thanks!



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Todd Terry
Re: Shooting at a higher frame rate
on Aug 2, 2013 at 8:07:13 pm

[stan welks] "60fps...will play back at normal speed in a 30fps or a 24fps Premiere..."

No, footage shot at 60fps will play back in slow motion if you drop it natively on a 30fps or 24p Premiere timeline. On a 30fps timeline it will appear as 50% of original speed. On a 24p timeline it will appear as 40% of original speed. If you want it to appear as normal speed you have to go to the original clip: MODIFY >> INTERPRET FOOTAGE >> USE THIS FRAME RATE and define whatever frame rate you want it to play back as... in this hypothetical case, 60fps.


[stan welks] "allows you to slow down footage in post and achieve better quality than footage shot at 24 or 30fps and slowed down?"

Definitely. Shooting at 60fps will allow you to display real slow-mo (just as an overcranked film camera would). Simply slowing down 30fps or 24fps footage gives you "fake" slo-mo, by simply duplicating frames, which gives a much jerkier and more stuttery look.


[stan welks] "are there reasons to not always shoot at 60fps in case you may want to slow footage down in post?"

You really should only shoot a higher-than-normal frame rate if you have a reason to do so... i.e., if you are planning for that to be a slow-mo shot. You should not shoot all of your footage at a higher frame rate just in case you might want to slow some of it down... maybe. The simple reason is that displaying 60fps footage at its native speed on a 24 or 30fps timeline simply won't look as good as footage shot at the "correct" frame rate. For one thing, your shutter speed at 60fps is going to be much higher than the shutter speed normally would for 24fps or 30fps footage... which is going to give all of your footage that staccato "narrow shutter" look that is likely not going to be appropriate for the look you want (note that I'm talking about shutter speed there, not frame rate... which are two easily confused yet totally different things). So DON'T shoot 60fps for normal-speed footage. Unless you are trying to replicate "Saving Private Ryan" or "Gladiator" or any of those other super narrow-shutter films.

Use 60fps for footage that you will slow-mo. Use 24fps or 30fps for normal-speed footage, depending on the frame rate of your project.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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stan welks
Re: Shooting at a higher frame rate
on Aug 2, 2013 at 8:49:37 pm

So if I have 60fps footage being brought into a 30fps Premiere Pro project:
1.) I choose Modify Clip > Assume this frame rate: and enter 30 fps in this location?
2.) Does this process degrade the quality of the video in any way?
3.) If I am shooting something with lots of action, perhaps a car race or a basketball game, and I want to slow down just a portion of my footage, what is the best way to approach this? Shoot the footage at 30fps and then stop the camera to change the settings to 60fps to shoot the footage I intend to slow down?

Thanks!



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stan welks
Re: Shooting at a higher frame rate
on Aug 2, 2013 at 8:51:12 pm

So if I have 60fps footage being brought into a 30fps Premiere Pro project:
1.) I choose Modify Clip > Assume this frame rate: and enter 30 fps in this location?
2.) Does this process degrade the quality of the video in any way?
3.) If I am shooting something with lots of action, perhaps a car race or a game, and I want to slow down just a portion of my footage, what is the best way to approach this? Shoot the footage at 30fps and then stop the camera to change the settings to 60fps to shoot the footage I intend to slow down?

Thanks!



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Todd Terry
Re: Shooting at a higher frame rate
on Aug 2, 2013 at 9:23:13 pm

[stan welks] "So if I have 60fps footage being brought into a 30fps Premiere Pro project:
1.) I choose Modify Clip > Assume this frame rate: and enter 30 fps in this location?"


It depends on what you want the results to be. If you have a 30fps timeline and put 60fps footage on it, if you want it to be 50% slow-mo, then you don't have to do anything... the footage will automatically be slow-mo.

Now, if you want to return it to normal speed, then yes... go MODIFY >> INTERPRET FOOTAGE >> ASSUME THIS FRAME RATE and put it 60 (or whatever the fps of the ORIGINAL clip was). Then it will play back on your timeline in normal speed. It might be slightly artifacty, and if there is a lot of motion in the shot it might appear a little stuttery (the narrow shutter look) because the footage was at a much higher than normal shutter speed for 30fps... at at least the motion will be right speed.


[stan welks] "Does this process degrade the quality of the video in any way?"

Yes.

It might introduce some motion artifacts.

It will, as I said, definitely appear more choppy and stuttery to restore normal speed motion from high fps footage, compared to footage shot at normal speed in the first place.

It's a bit complicated, but I'll try to explain why. It has to do with shutter speed (and again that's shutter, not fps). A "normal" shutter speed (one that mimics a 180° shutter in a film camera) is "one over twice the frame rate." Ergo, if you were shooting 24p then a "normal" shutter would be 1/48th of a second. Likewise for 30fps, a "normal" shutter speed is 1/60th of a second. If you shoot at a higher speed than that, the higher you go the more it eliminates the motion blur in each frame. Now, people might think that the sharper and less motion-blurry a frame, the better... but not true. Your brain needs that motion blur to interpret the strung-together frames as smooth motion. Now, lets say you want a slow-mo shot, so you shoot it at 60fps. Well in that case a "normal" shutter speed will be 1/120th of a second. That will look perfectly normal if you play it back at 60fps, and it will also give you a nice smooth slow-mo if you play it back at 24fps or 30fps, depending on your timeline. BUT... if you re-interpret the footage so that you get normal speed motion, that's as if you originally shot the footage at normal speed BUT with a 1/120th shutter, much MUCH higher than normal. Ergo, each individual frame is much sharper than it should be with almost no motion blur, and your brain interprets this as sort of choppy motion with a staccato look to it. That's what I meant by the "narrow shutter" look. That's done on purpose in a lot of action films to make scenes look more, well, "actiony." But unless you are wanting that look on purpose, it is usually very undesirable.


[stan welks] "If I am shooting something with lots of action, perhaps a car race or a game, and I want to slow down just a portion of my footage, what is the best way to approach this? Shoot the footage at 30fps and then stop the camera to change the settings to 60fps to shoot the footage I intend to slow down?"

Yes, exactly.

While you can slow-mo regular-speed footage to create "fake" slow-mo, and while you can reinterpret high-fps footage to give normal speed motion, neither of those options will look nearly as good as shooting the footage in the proper intended fps in the first place.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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jeff arballo
Re: Shooting at a higher frame rate
on Dec 29, 2013 at 3:08:38 pm

Not sure what he’s talking about. 60 frames will not automatically convert to 30 frames once dropped into a timeline. you need to convert or chafe the settings to 30 frames. Also i shoot all the time in 60 frames no 30 and it looks fine, so I’m not sure what he is talking about.


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Todd Terry
Re: Shooting at a higher frame rate
on Dec 30, 2013 at 2:00:20 am

[jeff arballo] "i shoot all the time in 60 frames no 30 and it looks fine, so I’m not sure what he is talking about."

You must not be shooting scenes with very much action in them then, or you would very definitely notice the difference.

Unless you are purposely changing it to something else, footage shot at 60fps will default to a shutter speed of 1/120th of a second. If, for example you use this in a 24p project you'll get a nice smooth 40% slow-mo. If, however, you wish to see this footage at normal speed and interpret it to play as such, you will indeed get normal speed as measured by time... it would be as if the footage was shot at 24fps. BUT it would be as if you shot it at 24fps but with a 1/120th of a second shutter... which is a much much higher shutter speed than would be considered "normal." As I tried to spell out above, a "normal" shutter (that is, one that emulates a 180° shutter in a film camera) will be "one over twice the frame rate"... or 1/48th of a second for 24fps (or 1/60th of a second at 30fps). A speed that slow will give a fair amount of motion blur in each individual frame. That might sound like a bad thing, but your brain needs that motion blur to interpret this series of still photos into smooth motion. The higher shutter speed of 1/120th will give sharper stills with each frame. An individual frame might look great... but seen at speed the action with look staccato.

If you have something static, or a talking head, you might not notice it. But if you have an actor dancing or jumping or running, you definitely will.

As I said, sometimes this effect is used on purpose... it can make action look more "actiony" which is why you see it used in some scenes of many movies. You also see this narrow-shutter look used more-or-less accidentally by a lot of local news and sports photographers who either think they are going to primarily be shooting for slow-mo, or because they just don't know any better.

That's what I'm talking about.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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jeff arballo
Re: Shooting at a higher frame rate
on Dec 30, 2013 at 3:49:13 am

what are you talking about default? The question was if I shoot at 60 frames do I need to transfer it to 30 frames. You said no it automatically does it. Not sure what your talking about it automatically doing it. I shoot both action and non action. If I need to change the speed of anything I transcode it to what I need. Don't know of anything where it just changes,Otherwise you wouldn't have programs that transcode your footage.


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Todd Terry
Re: Shooting at a higher frame rate
on Dec 30, 2013 at 4:36:52 am

[jeff arballo] "what are you talking about default?"

I was addressing shutter speed. I wasn't speaking at all (at least not in that post) about whether you need to reinterpret your footage speed on a timeline. That one's easy (and different NLEs behave and handle that differently). If it comes in on the timeline at the speed you want, then fine. If it doesn't, reinterpret it to the speed that you do want. No big deal.

No, what I was talking about was your camera's default shutter speed, which is a separately and entirely different thing than framerate. One of the original questions was basically why not shoot everything at 60fps... then you can slow-mo it if you want, or play it at normal speed if you want. The reason not to do that is because the shutter speed (by default) will be way too high (1/120th of a second) and much faster than normal (1/48th or 1/60th of a second) for normal-speed footage. Therefore motion footage will look a bit staccato because there is no motion blur in each frame. If there's a situation where you think your shot will be slow-mo, but you just might also need it in normal speed, then sure, shoot it at 60fps and sacrifice the motion blur for the sake of flexibility. But you shouldn't take the route of shooting everything at 60fps when you know most of it should be normal speed but just in case you might want a slow-mo shot out of it. That's just not a good path to the best images possible. It's not an iron-clad rule, but whenever possible you should shoot at a frame rate (and corresponding shutter speed) appropriate to how the footage will be finally used. There's no single "let's cover all the bases" setting that will look best for everything. Something will suffer.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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jeff arballo
Re: Shooting at a higher frame rate
on Dec 30, 2013 at 4:48:18 am

Yes I was just responding the his last post asking if he shot something at at 60 frames a second. I have shot in both and really never had a problem, although I do shoot most projects in 30 frames.


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Eddie Potros
Re: Shooting at a higher frame rate
on Apr 3, 2014 at 9:40:13 pm

I wonder how audio is affected by changing 60fps to 24fps?

Cheers,
Eddie11
http://eddiepotros.com
@e11world


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