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HD Downconversion

Published : 5th August 2003

I'm shooting greenscreen with the Sony F-900 for an eventual down-conversion to SD. The client likes "the pulldown look" and wants everything 23.98P. Will pulldown artifacts noticeably affect the composite (which will be made after downconversion)?

I expect no more so than 35mm shot 24fps and composited on SD video. Still, I wonder if there is a frame rate that is kinder and cleaner for eventual SD composites (say for instance 30p)? Any ideas?

Also, any experiences with Clearscan in regard to 23.98, shutter speed and sound sync? Am I right in thinking I lose the effect of the 1/48th shutter while using ECS, or can I have my ECS frequency and 1/48th shutter at the same time?

Douglas Cheney
DP, Los Angeles


You cannot have a double shutter 1/48 and a separate ECS shutter with the F900.

If you change from 1/48 to any other shutter that will be the effective shutter angle/exposure. FYI You are limited to the shutter angle/exposure choices at a particular frame rate 23.98psf versus 59.94i for example.

Tony Salgado

Good Questions
Quick Answers

Be more clear on Sound sync, What do you mean Sync Sound recorded separately Sync Sound recorded on Camera

If recorded Separately Run Sound at 29.97NDF and your Golden If on Camera It doesn't matter because the sound recording device is the HD Video Tape and you can run at any speed and the sound will always be perfectly in sync.

Now ECS is just a variable Shutter and because of that it only matches 1/48th when the variable shutter is set to 1/48th other than that look at the ECS number and imagine a 1/##.## or whatever ie: 1/66.85th or whatever you dial in.

23.98 Original then 3-2 Pulldown wont bother your Composite or your SD from SD
So Go for it.

Hope this helps

B. Sean Fairburn
HD Director of Photography
Castaic Ca

>I'm shooting greenscreen with the Sony F-900 for an eventual down->conversion to SD. The client likes "the pulldown look" and wants

The answer is: maybe. There are a lot of variables.

On the production end: Will the foreground subject have any sort of rapid motion? If so, the motion blur is going to be difficult to matte if you're starting at 23.98.

On the post end: What is being used to downconvert? What is being used to pull the mattes? How skilled is the person pulling the mattes?

And so on.

Bob Kertesz
BlueScreen LLC


>Will pulldown artifacts noticeably affect the composite (which will be >made after downconversion)?

Pull down removal is pretty much automatic at this point, so as long as the cadences are maintained should not be any particular problem. There will be no pull down artifacts, if done correctly.

Still would insist on doing VFX in HD land if it was my project, much better control of everything in everyway.

best of luck

Dermot Shane
HD & Film Vfx
Vancouver, Canada & Shanghai, China