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Shooting 25fps


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#1 Jamie Metzger

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Posted 02 July 2006 - 11:19 PM

If I shoot 25fps, that doesn't make it "PAL" does it? I've been confused about the workflow when shooting 25 and wanting to edit digitally... how would a program like FCP handle it? Does the digital signal only make it PAL?

I've been requested by my director to try this, and any advice you guys would have would be great.

Thanks.

BTW it's on the SR3, if that makes any difference. Oh and it's for a music video, so I assume I'd have to sync sound to 25 frames?
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#2 Charles MacDonald

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Posted 02 July 2006 - 11:47 PM

If I shoot 25fps, that doesn't make it "PAL" does it? I've been confused about the workflow when shooting 25 and wanting to edit digitally..

1) In Europe, it is traditional to shoot at 25 FPS, elsewhere 24 FPS is normal speed.
2) PAL (Phase Alternation Line) is the standard definition Televison system used in many countries arround the world that use 50 Hz power lines. Where 60Hz power lines are used, Televison has normaly been NTSC. PAL has slightly more scan lines, and so has slightly higher resoultion.

3) Depemding where you are and where your market is you would chose the frame rate accordingly. A 25FPS film will be off pitch is shown at 24 FPS... If going to video, you proably would want to use the one that is "right" for your PRIME market and accept a slight degradation in the other markets. For example if you are aiming for TV (standard ) in Canada you would use NTSC, or the HD equivelent. If you are aiming for Germany you would want the 50hZ version.

That said, it IS slightly easier to use 25FPS and transfer to a 50Hz video. going from 24FPS to 60Hz requires some real fancy stepping in the Telecine.

Your sound whould have to match the picture rate in any case, although that may be able ot be fudged a bit on a computer editing setup, as the time is constant. the 25FPS just has more frames to deal with :)

OH and just to add to the confusion that 60HZ TV signal is actually 59.9 HZ. due to some fancy math. I think that Pal is likwise just a bit less than 50Hz.
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#3 David Mullen ASC

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Posted 03 July 2006 - 01:17 AM

Why do you want to shoot at 25 fps instead of 24 fps anyway if NOT for 50i PAL post and broadcast?

NTSC is 30 fps / 60i, so when you shoot at 24 fps, you add a 3:2 pulldown to convert 24 frames into 60 fields.

So if you shot at 25 fps, transferred to NTSC, but wanted normal speed, then some other pulldown would have to be added to convert 25 into 60. It may be less smooth-looking than the standard 3:2 pulldown conversion, so the question is why shoot at 25 fps for an NTSC post?

Or you can transfer 25 fps at 24 fps so that the motion is very slightly slowed-down.

If you shoot at 25 fps and transfer to PAL, then every frame is converted into two fields, 25 into 50. In that case, usually if you shoot at 24 fps and transfer to PAL, you just transfer it at 25 fps and let the motion be slightly sped-up.
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#4 Laurent Andrieux

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Posted 04 July 2006 - 05:42 PM

1) In Europe, it is traditional to shoot at 25 FPS, elsewhere 24 FPS is normal speed.


Are you talking theaters or TV braodcasting ?

In Europe, the movie films speed is 24 FPS (though some theaters project at 25, unfortunaltly).

As for TV broadcasting, it is for sure 25 FPS (50 Hz) in Europe and many other countries (Pal is not in Europe only, some countries use 50 Hz Secam, in Europe and Africa) but it's 30 FPS (60 Hz) in NTSC countries (that are America and Japan).

If I'm right...

Anyway, for what is about the topic starter, since you are in US, why the hell use 25 FPS ?

Yes Pal is 25 FPS, but why do you want to produce in pal 25 FPS in "mean old frisco " ??

Shoot 24 (and 3:2 pull down as David says) or 30 FPS for NTSC.
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#5 Jamie Metzger

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Posted 04 July 2006 - 07:50 PM

Why do you want to shoot at 25 fps instead of 24 fps anyway if NOT for 50i PAL post and broadcast?

NTSC is 30 fps / 60i, so when you shoot at 24 fps, you add a 3:2 pulldown to convert 24 frames into 60 fields.

So if you shot at 25 fps, transferred to NTSC, but wanted normal speed, then some other pulldown would have to be added to convert 25 into 60. It may be less smooth-looking than the standard 3:2 pulldown conversion, so the question is why shoot at 25 fps for an NTSC post?

Or you can transfer 25 fps at 24 fps so that the motion is very slightly slowed-down.

If you shoot at 25 fps and transfer to PAL, then every frame is converted into two fields, 25 into 50. In that case, usually if you shoot at 24 fps and transfer to PAL, you just transfer it at 25 fps and let the motion be slightly sped-up.



After reading the responses I think I might have worded this wrong.

I would like to shoot at 25FPS, but I am going to using a DI (which I would need advice on later as well) and then editing on either AVID or FCP. Does there need to be a pulldown? Do american editing systems not handle 25 FPS well?

I would think it's just like shooting at 48 for slow motion, and playing it back at 24, right? Or is it playing it back at 48?

Either way, Would it look any bit different shooting 25, and in telecine transferring at 24? What would I do with shots that were 48 or 50 FPS?
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#6 David Mullen ASC

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Posted 04 July 2006 - 07:53 PM

You haven't answered the question why you are shooting at 25 fps instead of 24 fps, because the only answer that makes sense is that you are transferring to PAL for editing, otherwise you'd be shooting at 24 fps. When you tell us why you're shooting at 25 fps, maybe we can answer your question better.

As far as 48 fps, 50 fps, etc. if those were meant to be slow-motion shots, then you'd play them back at the "normal" speed of the rest of your footage. So the telecine would just transfer them at the same speed as everything else and they would look slow-motion as a result.

A D.I. would normally come after an AVID or FCP edit, not before. If you transfer 24 or 25 fps footage to NTSC with a 3:2 pulldown (i.e. run 25 fps at 24 fps), you would normally remove the pulldown when importing the video into the editing system in order to cut in a true 24-frame environment.
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#7 Jamie Metzger

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Posted 04 July 2006 - 08:01 PM

A "D.I." not being the same as Telecine I assume?

I wanted to shoot at 25, since I've been requested that by the director, and I figured I would give it a shot.

If it doesn't make much sense, then I won't try it, but if shooting 25, and then transferring at 24 gives a slightly better looking image, i might try and go with it.

So if I shoot 25, and transfer at 24, it's going to be just ever so slightly slower than 24, right? I might as well try it and let you guys know how it comes out.
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#8 Robert Hughes

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Posted 04 July 2006 - 08:21 PM

Umm, I'd like to help you out but I'm of the impression you're getting in over your head on this production. You are about to spend a lot of money on a non-standard work flow - do you have a good reason for this?

Your posts display a lack of familiarization with the process. My recommendation is to go to the library or bookstore right now and get out some good source books on film production techniques, before you commit time and money to the wrong plan.
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#9 David Mullen ASC

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Posted 04 July 2006 - 08:28 PM

Well, why does the director want to shoot at 25 fps? Because he's more concerned about the tempo of the editing in the PAL DVD & television release? That's the only reason I can think of -- he doesn't want his 24 fps movie to be sped-up to 25 fps when it gets shown on European TV or something.

If you are doing an NTSC transfer, the easy thing is to just pretend you are shooting at 24 fps when you are actually shooting at 25 fps -- by which I mean, you transfer at 24 fps with a 3:2 pulldown to convert to 60i NTSC. Your footage will be very, very slightly slow-motion looking.

The main issue with the whole 24/25 fps problem is audio more than picture -- you are either recording for 24 or 25 and speeding it up or slowing it down for the other, which affects the pitch unless you adjust it (movies shot at 25 fps and shown at 24 fps can make the actors sound deeper-voiced unless you do a pitch adjustment.)

It may also affect how the tempo of the movie feels.

But honestly, the only reason the director should be insisting on shooting at 25 fps is if he plans on posting it in a PAL country.

"Digital Intermediate" usually means that the film will be scanned into a digital form for color-correction, conforming, etc. and then recorded back to film, as opposed to cutting the negative and making a print using standard photochemical lab techniques. The telecine issue for dailies is usually a separate thing because you're just transferring to standard def video (PAL or NTSC) for offline editing in order to create an EDL.

From that EDL, you now have the option of going back to the negative and physically cutting it to match the EDL, and then striking a print, or whatever photochemical process is needed to get a printing negative -- or you use the EDL in order to go back and re-scan / re-transfer the negative to a high-end (i.e. expensive!) digital format like 2K or 4K, or the slightly cheaper 4:4:4 HDCAM-SR, using the EDL as a guide to just scan the shots you actually used in the final edit.

The only alternative approach would be to scan everything from the beginning to the high-end digital format you plan on using for the transfer back to film. Most people can't afford to transfer all the camera rolls up front to 2K, for example (although it's more common in Europe -- that's how "Band of Brothers" was posted, but that's partly because there wasn't as much HD infrastructure then). A few people will transfer everything to an HD format (hopefully the best ones, not the cheapest ones) and that transfer will also be used for the D.I.

But it is more common to transfer cheaply to standard def video just for video dailies, cut offline to generate an EDL, and never use those transfers again. Because they won't be used for the final project, they don't have to be high-quality. Although TV shows generally make the original transfer the basis for the final mastering.

As the term "intermediate" suggests, a D.I. most often describes "film-digital-film" -- i.e. the image is converted to a digital form and that is used to record back to film again.
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