Andy's DV tip #2
ASPECT RATIO
One of the single most important decisions you need to make before you shoot is:
What is your FINAL INTENDED ASPECT RATIO.
This issue is so often confusing for so many people, and it creates so many problems down the line that it's useful to bring some of it to light.
First, here are some definitions that are relevant to independent filmmakers:
- Your regular television is a 4x3 or 1.33 aspect ratio. that is, it's 4 units across and 3 units high.
- High Definition television is a 16x9 or 1.78 aspect ratio. That is, it's 16 units wide and 9 units high.
- Most films shot with spherical lenses are projected in America at 37x20 or 1.85
When shooting on MiniDV, you have 2 easy choices on most cameras. 4:3 or 16:9. It is VITAL that you choose one and stick with it, and it is VITAL that you know what you're primary intended aspect ratio is when you're all done.
Here are some considerations:
1) If you are intending on a video only output, in standard resolution video (i.e. your regular TV), and you want it full frame with no letterboxing, then 4:3 is how you want to shoot, because that is what you want as a final product.
2) If you are intending to bump up to High Definition or a film print for projection and/or you'd like a regular video version that is letterboxed (black bar across the top and bottom of the frame), then shooting in 16x9 is your best choice.
Some answers to common questions:
Q1) "My MiniDV or DVCAM camera does not have a "real" 16x9 CCD in it ... I hear that the 16x9 is "fake" and I shouldn't use it at all"
A1) Not entirely true. While a "true" 16x9 CCD is better than "interpolated" 16x9, the "true" 16x9 cameras are prohibitively expensive, and really overkill in many ways. Like the gameshow, your image chain is only as strong as it's weakest link. In the world of MiniDV and DVCAM, the weakest link BY FAR is the fact that the image data is 4:1:1 encoded and has a 5:1 lossy compression ratio (in essence that means that 80% of your image data is thrown out, and only a portion of that makes it back into the final image).
Thus, the weakest link (in terms of image loss) you need to be most concerned with is the amount of useable image that gets on tape.
Here's an interesting way to look at it:
If you shoot in 4:3 but you're intended output is HDTV at 16:9 or film at 1.85 (or letterbox NTSC), then the pixels that you throw away to crop for one of these formats are the EXACT SAME pixels that get thrown away from the CCD when you work in the "interpolated" 16x9 mode of most cameras. The huge difference is, that when you work in 4x3 and crop later, you are throwing away pixels AFTER the major 5:1 compression stage, with the end result being that 25% of your valuable data space on the TAPE is unused. (note that it can be worse than 25% - since the DV codec is fixed rate, if a high detail object (like a tree) is in that 25% unused image area it could soak up more than 25% of the available dataspace. YIKES!)
Thus, if you are going to end up in either 16x9 or 1.85, the exact same pixels of the CCD will still end up in the resultant frame, but if you shoot 16x9, those pixels are interpolated across a significantly greater data space and the result is a superior image.
FIGURES TO NOTE:
A 4x3 image cropped to 16x9 uses only 75% of the available pixels of the CCD and only 75% of the available data space on the tape.
A 16x9 "interpolated mode" image presented in 16x9 uses the EXACT SAME 75% of the pixels of the CCD as above, but has the advantage of using 100% of the available data space on the tape.
NEXT QUESTION!
Q2) I shot in 16x9 - but the distributor needs it in 4x3 and NOT letterboxed...what do I do now!?!
A2) Well, the only thing you can do is pan and scan the 16x9 image. If you took full advantage of the 16x9 frame that could mean spending a lot of time in After Effects or Final Cut Pro repositioning each frame.
But this points to why it is so important that you really determine what your FINAL requirements are. Failing to do so can lead you down a path that is both costly and detrimental to your film.
FINAL QUESTION;
Q3) If my camera does not have "real" 16x9, should I use that anamorphic lens in front of the camera instead of the interpolated 16x9 mode?
A3) From several reports, using the anamorphic lens does result in better images, especially if you are bumping up to film or HDTV. But in general, the lens adds additional complexity to your shoot and lowers your depth of field which can make focusing more difficult and critical. I'm told that it also reduces the long end of the telephoto of the zoom. I have heard reports that the Century Optics lens does work quite well. Don't forget cost though, too - You're working in DV to reduce costs. If you have multiple cameras, that means multiple lenses, and bigo bux.
Click Here for the next installment, where we answer "PAL or NTSC - The Big Question!"
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Till next time - happy shooting!
Andrew Somers is an editor, member of the Motion Pictures Editor's Guild,and is the Filmmakers Alliance Director of Technology, you can contact him viaGeneral Titles & Visual Effects --
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