Mixing It All Up: 4:3 with 16:9… and a Green-Screen! Help.

[Tony Kloiber]

OK,
The short term helpful stuff first….
A pixel is not a pixel. They come in differing aspect ratios. 16×9 will be anamorphic (taller and thiner for those look at things from a relative perceptive) a greater ratio H to W. You can shoot and key a 4×3 clip and then put it into a 16×9 comp but pay attention to the pixel aspect ratios.

Also the new P2 camera doesn’t narrow it down enough for me but, if you mean the HVX-200, the camera can shoot in many formats including DVCProHD which will give you a lot more pixels to work with.

The long term….
[Alex Kuzelicki] ” I noticed that the 16:9 setting of our practice camera actually made getting good shots a lot harder than the 4:3 setting. For example, someone flying up and out of frame really quickly is much easier to catch in 4:3 because you have so much more of a frame to work with. “

Practice camera? If you not using the same camera and lens your going to seeing something different than the practice camera.

“More frame to work with” is a function of focal length, imaging area and distance to subject if the 16×9 frame is to tight move back. All things being equal a 16×9 frame will have more room side to side and the same top to bottom.

TonyTony

[Mylenium]

[Alex Kuzelicki] “I figure that since I’m taking the green out anyway, and then putting the subject in a new (16:9) world it shouldn’t matter what aspect ratio I captured the subject in… should it? A pixel’s a pixel right?”

Nope. Like Dave and Tony said – get yourself educated in aspect ratios. Also know what formats your camera actually can shoot – if it’s a P2, I assume it’s most likely going to be HD 720p/i. As for having more frame to work with in 4:3 – hone your skills as a cam operator. There is no way around this. Shooting 16;9 is different as is HD different from SD (longer lenses and stuff). Also make your stuntmen/ actors/ talents realise that they have to be more disciplined. From what you say, it sounds like you are simply not able to repeat shots identically and want to compensate for that in post. If it helps, add some markers to your green screen. This wil lgo a great way towards giving you a better impression where things actually are while you are panning and zooming.

Mylenium

[Pour Myl

[Alex Kuzelicki]

Thanks Mylenium and everyone that replied,

With every post reply things are getting clearer but, you’re right, I definitely need to get educated on pixel aspect ratios and formats, etc. Which is exactly why I’m asking all these questions. Your advice is very much appreciated (and needed).

I’ve done some searches but it would be fantastic if someone could just explain it simply, especially as there are these higher resolutions with HD. Sorry for my naivety. This forum has been the best teacher I can find.

Maybe someone could set me straight on these two points:

1) 16:9 stretches pixels vertically so they can be unstretched out in 16:9 project or on a 16:9 monitor? Is that right? So the 16:9 camera (say the Panasonic HVX200E) actually distorts the pixels to get more resolution and, in After Effects, you need to Interpret the Footage as 16:9 to display and output it correctly?

2) Computer pixels are square, right? And video pixels are rectangular? But rectangular which way? I’m guessing they are ‘long’, rather than ‘tall’? But what confuses me is that 16:9 pixels are ‘tall’, aren’t they? So, doesn’t this kind of confuse things when you want to composite, say, artwork made in a square pixel program. It certainly confused me!

Perhaps someone can help. Sorry for my inexperience.

Thanks in advance,

ALEX

Just a note on the stunt work – My stuntmen are top professionals (have worked on all the Matrix films, Mission Impossible II, Superman and on and on). We’re doing advanced wire work with complex timings, acrobatics and equipment so, despite what you see on the “Behind the Scenes” of DVD’s, etc it’s often a matter of just doing it again and again until all the elements: the camera, the performer, the ‘pullers’ (or sometimes equipment like the winch or the air-ram) all gel together and you get a good take. I’ve worked on many ‘hundred million dollar films’ where they’ve shot up to 70 takes to get it right. Speaking from real world experience…

… of course, that said, I don’t have this luxury with my ultra low-budget music vid… so I really do need all the help I can get. Thanks so much for your advice so far.

[Steve Roberts]

Search the COW tutorials for an article by Rick Gerard on non-square pixels. (pixel madness)

NTSC SD pixels are tall and skinny. This is why something that is 720×480 looks like 4:3 on a TV, but not on a computer. If you’re looking at square pixels, 720×480 is not 4:3 — that’s why 720×480 SD looks wide on a computer.
720×480 widescreen uses wide pixels, so it looks narrow on a computer monitor which uses square pixels.

Everything looks right in the proper situation.

1920×1080 is square pixels and 16:9. Do the math: 1920/16=120, and 1080×9=120. Therefore, 1920×1080 is 16:9 square pixels.
1440×1080 is something of a compromise to try to fit HD onto a chip.
1280×720 is also 16:9 square pixels. In this case the common factor is 80, not 120.

1) Regarding the HVX, if you’re shooting 720p, you interpret the footage (captured in FCP, probably) as 1280×720 square pixels. Works for me.
2) Welcome to non-square pixels. If you’re in photoshop, and you’re going to SD, you can work in 648×486 (or 720×540) if you’re going to 720×486, or 640×480 (or 720×534) if you’re going to 720×480. If you’re going to SD widescreen, work in 864×486 or 864×480 respectively. If you’re going to HD (which is always 16:9, by the way) you can work in 1280×720 or 1920×1080.

Does that help?

[Alex Kuzelicki]

Whoah!

Thanks Steve. That helps A LOT!

Very much appreciated.

ALEX

[Steve Roberts]

Actually, I just made that all up … 🙂

Good luck, and show us the footage when you’re done if you can. Stunts are cool.

[Alex Kuzelicki]

“… just made it all up.”

You scared me for a minute there. Very funny.

Thanks again,

ALEX