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Quick 24p question

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Anne Lawant
Quick 24p question
on May 1, 2010 at 11:16:59 pm

So here's a simple, quick question about the 24p mode on my Canon 7D. It doesn't shoot 24p but something like 23.47p. Being European, I get uncomfortable with framerates that aren't integers. What does this mean? Why isn't it really 24p? Does it matter?

Thanks and greetings,
-Anne Lawant


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Bob Dix
Re: Quick 24p question
on May 2, 2010 at 12:14:34 am

Anne,
Ask the experts at Canon, I understand the decimals are splitting straws, when in fact it is 24p which is the motion picture frame rate. When editing in Premiere Pro I cannot tell the difference and certainly in Australia an undetectable difference to 25fps which looks cleaner than other frame rates in PAL.
The video out of the 7D and 5D is stunning at any frame rate ?
I was shooting 30fps on a Canon EOS 5D mark II in New Zealand and Egypt last year and the edited clips @ 30fps and now 25fps (After the Firmware update 2.0.4) out of Premiere looked very, very good.

Freelance Imaging & Video
AUSTRALIA


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Jonathan Ziegler
Re: Quick 24p question
on May 2, 2010 at 2:28:48 am

Anne, do you want the long answer or the short one? ;)

Short answer is NTSC is not a true 30fps, it's 29.97 fps (long answer here). Sooo, 24p isn't a true 24 fps, it's 24 fps using a 2:3 field pulldown to be pretty close to 24 fps when using NTSC. Consequently, 24P is actually 23.976 fps. The P just means progressive and it means you capture 2 fields at once (like film captures an entire frame or 2 fields).

Your NLE should still handle it. If you are planning on going to PAL, it's the same conversion you would use going from 24 to 25fps. Don't worry about the frame rate, you lose something like 2.4 frames every 100 seconds at 24P (3 for 30P).

Hopefully, Canon or some other DSLR maker will come out with 24PA mode - a different pulldown method that allows you to capture a fairly true 24fps that your NLE will be able to convert more directly to a true 24fps. We're not there yet.

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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Bouke Vahl
Re: Quick 24p question
on May 2, 2010 at 8:59:51 am

Jon is partly right.

23.976 can be speeded up to 24, but you need to do something with the audio as well, or you get out of sync.
even if the speed difference is just 0.1%, over a 10 minute clip that means 60 * 10 * 0.001 = 0.6 seconds, and that is VERY noticable
Go to my site, download QTchange (it's free), it will do that for you.

It highly depends on your desired output what to do.
For the DVD market, you can put 23.976 on DVD, and it will play fine in Europe.
For going out to film, you need to speed up to 24
For going out to PAL, you need to speed up to 25. (not uncommon, all major movies are broadcasted this way. Check out the running time for the film in a theatre vs the running time on TV)

As for the AP pulldown, this is nonsense. The only way AP applies if you record 24 to tape that does not accept other framerates.
In digital recording, the way it is is just fine. If you need to add pulldown to go to broadcast, you don't use AP but NP, and you do it after your editing so the cadence stays. (Almost all broadcasters require this).

hth,



Bouke

http://www.videotoolshed.com/
smart tools for video pros


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Noah Kadner
Re: Quick 24p question
on May 2, 2010 at 7:33:57 pm

24p = 23.976= what all 24p cameras and post workflows use.

24 frames per second exact- what film cameras and some high-end digital cameras like RED are capable of shooting. But I recommend shooting 24p/23.976 unless you have a really good reason that your post-personnel agrees with.

Noah

Check out my book: RED: The Ultimate Guide to Using the Revolutionary Camera!
Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Sony EX1 Guidebook, Panasonic HVX200, Canon EOS 5D Mark II and Canon 7D.
Watch Formosa- My indie movie shot with the SDX900 and finished with Final Cut Studio.


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