24p and slo mo

[Graeme Nattress]

If you shoot 24p to edit in a 29.97fps timeline, the 24p will have 3:2 pulldown in it, which unless removed first, will look really dodgy in a slowdown. What I’d be tempted to do is shoot in 24pA and edit in a 23.98fps timeline so that you don’t have any pulldown. This will therefore lead to two good slowmo speeds as follows:

shoot 30p and conform to 23.98fps in Cinema Tools for a subtle 80% slomo, perfect quality
shoot 60i and conform to 23.98fps, then slow to 50% for a nice looking 40% slowmo

I’d not shoot at 1/500th shutter unless you want that Gladiator battle high shutter speed look. I’d shoot with the standard, 1/48th I think for 24p, and either 1/60th or 1/120th for the slowmo stuff, based upon experimentation.

Graeme

– http://www.nattress.com – Film Effects and Standards Conversion for FCP

[Andrew Schuurmann]

Graeme, if we ever meet I owe you a beer (or ten) — you always give great insight. But, now I’m left with more questions:
Until I get into the edit, I won’t know which footage I need to slow down and which I want to keep full speed (this is a live event capture, so we’re not sure what we’re going to get). 80% is not slow enough for what we want to do, so 40% sounds better. Would you recommend running all the cameras at 60i with a 1/60th or 1/120th shutter and then conforming to 23.98? What about the footage we shoot at 60i that we want to play full speed? How should we conform that? I’m planning to master to DVCPro50 for playback on LED screens.
Also, I’m planning to capture over SDI and not FW — will I lose my flag information that way? Or do I just need to make sure my capture settings are correct?
Thanks again.

Andrew

[Graeme Nattress]

I don’t know about capture flags for DVCpro50 over SDI. Unless there’s some very particular reason, I don’t see why FW won’t suffice for DVCpro50 though.

For best slowmo, there’s a couple of options really – shoot at as high a frame rate as you can, or use fancy expensive slow rendering plugins like Twixtor to magic in the extra frames.

What I’m advising is shooting at as high a frame rate as possible, and then, for more slowmo, using the best quality option, which would be to play fields back as if they were frames, giving an instant, high quality 50%. Add in that you’re going from 60i to 24p, that gives an extra few percent, getting a lovely 40% for you.

Now, if the rest of the edit is going to be 24p, then that leaves a big problem, as you’d have to convert the 60i to 24p. That can be done, and indeed I have my plugins which will do it for you nicely, but it’s always better to shoot real 24p for 24p if you can.

I see that you have two choices –

1) shoot 24pA, edit 23.98fps, have great looking 24p, accept that slowdown will look not too hot, or extensive twixtor render times.

2) shoot 60i, get great 40% and 80% slowdowns with little render time, but have to convert the 60i to 24p for the normal speed stuff, which can never look quite as good as real 24p.

Obbiously, a hybrid between the two would be best, shooting 60i when you know that it needs to go slow, and 24p for normal speed stuff, but it doesn’t sound like that’s possible. The good thing is, there’s solutions whichever way you want to go, but I don’t think either is perfect.

Hope that helps,

Graeme

– http://www.nattress.com – Film Effects and Standards Conversion for FCP

[Annaël Beauchemin]

> I’d not shoot at 1/500th shutter unless you want that Gladiator battle high shutter speed look. I’d shoot with the standard,
> 1/48th I think for 24p, and either 1/60th or 1/120th for the slowmo stuff, based upon experimentation

This is interesting.

I’m not sure why the standard shutter speed would be better than a higher speed shutter for slowmo. In my experience, the motion blur of low shutter speed can create a randomly “throbbing” motion when slowed down. Sharp footage does also work way better with twixtor or the like.

But I do have less experience than you… so why do you recommend the standard shutter speed?

[Graeme Nattress]

I just like how it looks. I find that too high a shutter speed looks odd, I guess 1/500th as suggested sounded rather high to me. I guess that if normal video looks fine at 1/60th, for the same kind of look at say 50%, then 1/120th might be more appropriate. Also, as it sounds like we don’t know which video will be slowed down, and which will not, that shooting it all at high shutter speed might look odd… So nothing definate from me, just thoughts….

Graeme

– http://www.nattress.com – Film Effects and Standards Conversion for FCP

[Andrew Schuurmann]

Thanks again, Graeme. 60i it is, and I might lean to 1/120th for shutter speed (I kinda like that look). Reality is about 80% of the footage is going to be slowed down, so I’m happy taking my chances at 60i.
The reason I asked about flags over SDI is that the only deck I have doesn’t have the FW option, and I can’t rent since I blew all the rental $$ on the SDX900s. If I have time I might do a little test over SDI and post the results.

Andrew

[Annaël Beauchemin]

> Also, as it sounds like we don’t know which video will be slowed down, and which will not, that shooting it all at high shutter
> speed might look odd…

I’ve never really shot as high as 1/500 since it requires lots of light, but I agree that shutter speeds which aren’t a multiple of the recording FPS look odd.

To me, higher shutter speed just look sharper in the motion since there’s less motion blur. To some point, it might flicker so much it’s sharp. But at least all frames are equally “motion blured” (or as sharp).

I feel that handheld footage is the most problematic footage to be slowed down because some frames are sharp, some others not because of the uneven motion of the camera. Played back at full speed we don’t notice it since it feels natural. When slowed down, the motion blur becomes visible and stops being “natural” since the motion itself is much slower. I think higher shutter speeds (and turning off the image stabiliser) might help to reduce this unequal motion blur.

[Jeremy Garchow]

I think that depends on your capture card Andrew (whether or not the ‘flagged’ frames will be removed on capture). I’m not for sure, but I think Aurora is the only capture card that can remove 3:2 pulldown on the fly. I just completed a project on an SDX (we didn’t have your slow motion requirements) and we ended up deciding to shot 24pN (29.97 editing timebase). I have a Kona 2 and I called AJA and asked them if the K2 would be able to remove any pulldown (3:2 or advanced) on the fly. They said it is possible to remove advanced pulldown by tweaking some settings, but there’s a huge caveat. You have to make sure that the start frame of every capture is on an A frame. I simply did not have the time or quite honestly, the patience to make sure that every frame of my capture was starting on a A frame. What capture card do you have?

If 80% of this video is going to be slow motion, I would suggest twixtor for the best results. Also, here’s a link on how to use 60i footage to make slo 24p footage out of after effects:

https://www.rarevision.com/articles/slow_motion.php#

Break a leg out there

Jeremy

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