24p System question
 

Hello all, new here. Sorry if this was covered elsewhere...

Under VIDEO SET in the menu, I can't seem to find a layman's explanation of the difference in shooting 24p as 60i or (as it's listed) 24PsF. To me they both look the same, take up the same space, etc. The only difference I've noticed is the footage doesn't pop up as fast when opening Log and Transfer in FCP once I've shot 24PsF.

Thank you in advance.

Welcome to the forum!

They're both stored in interlaced streams. The former requires pull-down removal, the latter does not - as such, the only real difference is in how they're handled by NLE's.

So although it says "P" it is not a true progressive image? You say they are both interlaced streams. And the 60i requires pulldown removal?

Hi Edwin,

It is a true progressive image, but it is stored in an interlaced format for compatibility reasons.

What makes an image progressive is that all lines are read/captured (from the sensor) at the same time (actually in succession).

When an interlaced image is captured this is not the case and only half the lines are captured at the same time, resulting in two fields (odd and even). There is a time difference between these fields (with 60i that is 1/60 of a second). This is why if you put two fields from an interlaced image together things may not "line up" properly" (and fast moving things may only show up in one of the fields, etc.).

With a progressive image things always "line up", even if it is stored in an interlaced format. You just put the two halves together to get a seamless image. Your editing software will do that for you automagically on import.

George/

P.S. With CMOS sensors there is a time difference between when the first line is read and the last line of an image. This is the reason CMOS sensors can have "skew". CCD's work differently and don't have that issue (they have other issues like heat).

Thank you George. So is it safe to say you would prefer to shoot 24p as 24PsF and not 60i so as to avoid a potential mishap? I'm still trying to decipher these two options.

Edwin,

I'm in PAL land, and have been using 25PsF ever since I got my EX1 almost 3 years ago without problems. I never use 24p, but if I did, I'd certainly choose PsF.

Those more knowledgeable in 60i editing might advise you better, but still I HTH.

Piotr

Thanks for your help.

I shoot 24PsF any time shooting 24fps. Just makes post production life so much easier.

-Garrett

Hi Garrett. Can you explain what you mean by this? I'm trying to get as much information as possible.

Also would 24PsF be ideal for transferring to film?

Thank you.

Hi Edwin,

Saving 24p in a 60i timeline requires the insertion of frames to act as place holders on the 60i timeline. Since 24p has 23.976 frames per second and 60i has 29.97 frames per second (or 59.94 half frames per second) there has to be additional frames put on the timeline in order for 24 frames to keep correct time on a 60i timeline. This is called pull-down or 3:2 Pulldown. Here is a link that helps to explain this process:

Final Cut Pro 7 User Manual

In order to correctly edit in most NLE's you need to remove the pulldown. To add to the fun, there is another form of pulldown, 2:3:3:2 or advanced pulldown that some cameras use. Correctly removing the pulldown can be tricky and cause headaches for some editors (it's not really rocket science but I've worked with some newbie editors that have problems with this). So it's just easier to shoot 24PsF which is straight forward 23.976 frames per second saved on a timeline that has 23.976 frames per second.

Hope that doesn't create more confusion than help to explain things.

-Garrett

Garrett, very helpful. Thank you!

Am I missing something, I can only see 25P (pal) or 24P (ntsc) on my EX3, I can't see any PsF option in either NTSC or PAL.

I have been shooting most of my recent work in the 24p format, this frame rate is easier to sell - so I am told by my film library (Getty)

Not sure about the EX3 but on the EX1R, there is a top level menu called Video Set. One of the items in there is called 24p System. That setting can be set to 60i or 24PsF.

Handling multicamera 24p
 

On a related topic, if you had a b-camera that didn't have 24PsF, would you still shoot the EX in 24PsF and convert the b-camera in the NLE or would you shoot the EX in 24p-60i?

I think there is some confusion, the setting you are talking about 60i or PSF is not for recording it is for the signal out of the SDI output of the camera, so you can select how you want your output of the 23.97 capture as a 60i stream or as a segmented frame.

greetings