When to use 25p & when not?

[Clayton Hairs]

Hi all

This might seem a little unsophisticated but I've recently bought the new XL2 (after bashing my XL1 to the teeth for six years)...and it's the 25p progressive scan option which does me over...

My question is when to use it?

I've read on quite a few boards that the primary reason for doing so would be to get the 'film look' and although this is desirable I'm a little concerned that since a lot of the doc I've been shooting on has been shot on trad. interlaced 50 (whatever it is) and that intercutting the 25p with the rest will not give the piece some semblenace of visual continuity...

any thoughts would be most helpful...

[Rob Lohman]

Your concern is understandable and mostly true as well. Due to
the different capture methods progressive has a very different
temporal signature than interlaced. Depending on the amount
of motion in your scene (by the camera or objects you are shooting)
it can look very different and indeed look strange in combination
with other footage. Whether or not this is a problem depends on
the doc your making and the sections this difference would be
in. If you don't want any difference I would suggest to shoot in
just plain old interlaced!

[Clayton Hairs]

Thanks Rob your comments give me thoughtfood...cheers!

[Dennis Hingsberg]

In PAL based world, 25p would be most useful for transferring to 24fps film, and is basically like the frame mode of the XL1 but with the full resolution offered by the CCD. It's like a pseudo "film look" that got everyone excited here in North America when it was first realized the XL1 first had it.

If you shoot everything 50i, you can always deinterlace in post to regenerate a "progressive" looking image. Of course some resolution may get lost, but that will depend on what software and method you use of course.

50i = reality tv shows
25p = film motion

[Joshua Litle]

I concur that there will be a visual mismatch intercutting 25i and 25P footage.

This thread seems a spot to post a question. When transfer 25i to film at a 1:1 frame rate, I assume it's necessary to de-interlace (resulting in some loss of vertical resolution) to 25P first?

[Dennis Hingsberg]

De-interlacing is not straight cut, nor that well understood I find.

Most people would tell you that when you deinterlace in post you end up with half the resolution because the fields are blended together to make a full frame. Other will tell you that when you deinterlace you interpolate fields to create a new frame and only a bit of resolution gets lost this way - say only 25%. Wrong again. (I have no idea where these numbers come from?!) Some will swear their deinterlacing results have been amazing... while others will curse it.

The truth about deinterlacing is there are a variety of methods, some of which utilize complex algorithms and calculations to remove deinterlace artifacting - and others that for the most part really just "blend" fields. Honestly, no two deinterlacing processes are the same.

Having said that, if you're planning to transfer to film you should ask the transfer house how exactly they will go about creating progressive full frames from your footage and ask them directly what kind of vertical resolution loss you might expect.

[Joshua Litle]

but i am correct in saying that de-interlacing will be necessary at some point in the PAL to Film process, even if it's a 25 PAL > 25 FPS Film transfer?

[Dennis Hingsberg]

For the best look you should deinterlace, but actually no you don't have to deinterlace at all. But then you end up with deinterlace artifacting on film print - this is that stairstepping looking effect on objects in motion and looks awful.

[Graham Jones]

'but i am correct in saying that de-interlacing will be necessary at some point in the PAL to Film process, even if it's a 25 PAL > 25 FPS Film transfer?'

1. undeinterlaced 25i -- film = horrific

2. deinterlaced 25i -- film = clearly video originated

3. 25p -- film = has potential, depending on all the other technical and production elements of course


Of course, no's 1 and 2 can be used if the viewer is okay knowing 'n feeling they're watching video.. see Farehneit 911