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Old December 30th, 2005, 09:40 AM   #1
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key question about 24p vs. 60p

I'm planning to shoot a documentary film with the HVX200 at 1280x720 and I have a very important question to ask about 24p vs. 60p.

I saw the clips posted by Kako Ito. They all look awesome BTW.

But I notice that 60p is a lot smoother than 24p for anything involving motion, less strobic looking.

Is there any way to get rid of the strobe like look you get with 24p when shooting people or machines in motion?

In one of Kako's 24p clips showing a car paused at an intersection with other cars driving by, the movement of the cars traveling appears strobe-like, not smooth.

Is there any way to avoid this in 24p? Or will all movement in 24p inevitably have that strobelike look?

Would increasing the shutter speed eliminate the strobe like look of 24p or would it be better to shoot in 60p if you plan to shoot people / machines in motion???

Thank you very much in advance to anyone who can enlighten me here.

- Nicholas
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Old December 30th, 2005, 11:03 AM   #2
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That is the THE problem with 24p. The frame rate is not fast enough for anything but slow motion across the field of view. Lots and lots of film information if you search that gives shooting angles and motion information to limit the effects of slow frame rate of 24fps film that mostly apply to the video 24p. Shoot at a high frame rate then apply whatever effects you want after but at least you will have a clear image to work with. To me the real value of the HVX200 is the fact it can shoot at 60P. You can always make it strobe if you really want to emulate the technical limitations of the old film technology !!!

Ron Evans
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Old December 30th, 2005, 11:19 AM   #3
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Your frame rate will also depend on how your project will be displayed. If you're going for a video-only release then 60P or 30P (if you want more of a film look) will be just fine. If you plan on a filmout then 24P is a must. Also, if you're planning on international distribution 24P will give you a much better looking conversion for PAL conutries as it will not need the interpolation that 60P and 30P will require.
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Old December 30th, 2005, 11:33 AM   #4
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If you shoot 60p, how do you play back that on your TV at normal speed? Doesn't a TV play at 24p or 30p? Would you need to speed up the 60p signal?
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Old December 30th, 2005, 01:09 PM   #5
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Dear Ron and Kenn,

Thank you both for your input. Kenn, do you mean that if I were to go with 24p and I had to shoot motion - for example cars driving at 65Mph down a freeway, that I should increase the shutter speed to say 125? 250? 500????

Suppose I wanted to shoot a freeway scene at night at 24P? That would look very strobic, so would it be then better to shoot at 60P, then import that footage into a 24p project and render?

Thanks for any further feedback you can give me.

James, in answer to your question, I believe TV frame rate in North America is always 29.97 per second and in Europe and everywhere else, 25 FPS.
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Old December 30th, 2005, 01:42 PM   #6
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Quote:
Originally Posted by James Darren
If you shoot 60p, how do you play back that on your TV at normal speed? Doesn't a TV play at 24p or 30p? Would you need to speed up the 60p signal?
No, not at all. Traditional interlaced TVs, like standard-def TVs, play at 60 interlaced fields per second. The 60P signal would be converted on a field-for-frame basis, so 60p becomes 60i.

Newer high-def TVs can play 24p or 30p or 60p, so on those it's a direct playback situation. The ATSC ensconced three broadcast methods for 720p, being 720/24p, 720/30p, and 720/60p. So any TV that claims to be ATSC-compatible has to support all those playback rates.
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Old December 30th, 2005, 04:40 PM   #7
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Nicholas
CHanging shutter speed will change how sharp the image is but will not have any effect on the 24p stutter which is just too slow for fast motion. You will get a nice sharp, strobing image. You are correct that frame rate in NA is roughly 30 and most of the rest of the world is 25 but in all these cases the TV is intended to be interlaced ( 60 for NA and 50 in PAL land, initial TV's taking advantage of the mains AC electricity frequency, which just brings it above the flicker rate for the eye brain to perceive as smooth motion). It really isn't but our brains are convinced its OK, especially with the decay in the CRT phosphors between interlaced fields. For those of us from NA when we visit UK for example the TV's appear to strobe until our brains convince us its OK, for me it takes two or three days. The 60 to 50 cycles is noticable. With modern electronics and progressive displays with high refresh rates it is possible to solve all these problems as long as we don't try and reproduce the past!!!!

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Old December 30th, 2005, 05:16 PM   #8
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To answer the question regarding shooting for slo mo.
Use the fastest frame rate possible and yes use faster shutter speeds. The shutter speed should roughly match the target not the shooting frame rate. If not the MB becomes too much, it doesn't match the new speed of the clip.
Same goes for footage that you know will need stabilisation in post, nothing looks wieder than motion blur trails that don't match the motion.
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Old December 30th, 2005, 10:22 PM   #9
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Back to the 24p / 60p question

I also noticed the strobe on the 1080/24p clips, however the clip labled 1080/24pa seemed smooth. This might be because there wasn't as much gross motion. This was seen thru FCP, the clips just dropped in to the sequence and played without rendering. I went frame by frame and the strobe is very clear and very interlaced in the 24p clip. Does anyone have an answer for why this is so?

Waiting to see 720/24p clips.
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Old December 30th, 2005, 11:18 PM   #10
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Quote:
Originally Posted by William Hohauser
I also noticed the strobe on the 1080/24p clips, however the clip labled 1080/24pa seemed smooth. This might be because there wasn't as much gross motion. This was seen thru FCP, the clips just dropped in to the sequence and played without rendering. I went frame by frame and the strobe is very clear and very interlaced in the 24p clip. Does anyone have an answer for why this is so?

Waiting to see 720/24p clips.
24pa is made for watching 24 frame on 60i, 24p should be actually treated and edit in the 24p timeline.
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Old December 31st, 2005, 01:34 PM   #11
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That makes sense. Thanks for the answer. And thanks for the clips.

I tried to import it into a 24p timeline but they all required rendering. The standard DVCPro HD timeline was the only one that accepted the clip straight. Is there a FCP preset sequence setting made for the 1080/24p clips? I only see 720/24p presets.
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Old December 31st, 2005, 02:32 PM   #12
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Quote:
Originally Posted by William Hohauser
I tried to import it into a 24p timeline but they all required rendering. The standard DVCPro HD timeline was the only one that accepted the clip straight. Is there a FCP preset sequence setting made for the 1080/24p clips? I only see 720/24p presets.
was wondering about the same thing... does 5.0.4 have presets for 1080 24P/30P?
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Old December 31st, 2005, 06:17 PM   #13
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I was wondering the same thing as the above posters. When I play the clips that Kaku uploaded I noticed alot of interlacing which was surprising considering that I was expecting deinterlaced frames for 1080p24. I'm using FCP 5.0.4 and I don't see a preset for DVCPRO HD 1080p24. How do I play these clips back properly in FCP?
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Old December 31st, 2005, 08:41 PM   #14
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What I'm seeing is that the 1080p24 clips are in 29.97 fps so they have pulldown added. The clips are Interlaced Upper field first. One would have to reverse telecine them back to 24p (23.98). This is much like the 24p in the DVX100 series.

The 60p clips are at 59.94 fps and are progressive.

In FCP you can create a custom preset. Not sure if that would preclude rendering though
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Old January 1st, 2006, 01:01 AM   #15
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filming animals running at 24P?

Don and everyone else, thank you very much for your continued feedback.

Now, suppose I were shooting a nature documentary about how cheetahs hunt their prey for example: we're talking about a lot of fast motion here.

What would would be the minimum shutter speed I would need in broad daylight if I wanted to shoot at 24p?

Or would I be much better off shooting at 60p???

If I did go with 60p, would it be a lot harder to transfer to film than 24p???

I guess what I am not understanding is that when you go to the cinema and watch a movie, you don't see the strobing that you get with 24p "filmlike" video. Is that because you're looking at genuine film (16mm/35mm/70mm) shot at the right shutter speed?

Will the 24p look always inevitably look stuttery/strobic?

Am I understanding it correctly then, that all motion shot at 24p will look strobic, not smooth. If so, then how fast a shutter speed does it take to get rid of the strobe-like quality of 24p????

Sorry for all these questions, but choosing the right recording mode will be a crucial decision for me before I begin shooting.

Thank you in advance,

- Nicholas
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