Scott Rachal

I'm really scraping the bottom of the memory barrel here, but I seem to recall that an official CCIR-601 spec image has 242.5 scan lines per field. (486 lines total, with the last line of field 1 and the first line of field 2 being 1/2 lines) See the first graph here: Field Dominance This explains the partial lines at the top and bottom of your viewfinder (and your captured image if you use a CCIR-601 capture card to capture the images from DVCPRO tape) The DVX 100a, being a DV camcorder, using the DV spec of 480 lines, (Not 486) has 240 full lines per field. I remember seeing those partial lines on any broadcast camera I've ever shot with. Its just NTSC, nothing to do with the SDX900 in particular. I think this all harkens back to the analog broadcast specs (3.58 MhZ bandwidth X 29.97 cycles per second) etcetera.... that's where the 'partial' lines originate. -Scott

We are using "Keylight" in AE 6.0. Yes, the edges did get out of hand a bit, because of the "hurried" lighting on the green screen. Most of the shots from this shoot keyed very nicely though. I just pulled this as an example of some of the pitfalls that await after a green screen shoot...

Another shot: Note the green edges on her right arm: Same shot filled with color, no blur worries: Is this how you are going to treat your dancers?

Regarding VRES Progressive or Interlaced, ONLY use the Progressive setting if the final product will NEVER be shown on an interlaced display. In your case, if video tape or DVD displayed on an interlaced CRT is how the final will be viewed, shoot in the Interlaced mode. The Progressive setting is intended for film out. I have been tempted to use it when the final distribution is planned to be internet video only, but the client always decides to release on DVD or vhs, and if that happens, the footage shot in the Progressive VRES mode will have unnacceptable interlace twitter. (I've tried it, it looks REALLY flickery) -crow

I planned to play the 30p aquisition at 24 fps in the edit to get a 20% slo-mo. I shot this with the 1/48th shutter because I wanted the slowed-down frames to look as if they were shot at 24 fps with a 180 degree shutter angle (1/48th sec) Only in post did I see how the blurred edges of motion caused my mattes to be a little harsher than I would have liked. I didn't take my advice because I hadn't been bitten by the blurred edges yet. So you are getting the benefit of my pain and suffering. (And next green screen shoot, I'll take my advice, you betcha) Most of the blur problem has to do with spill suppression issues. If you are going to pull a matte, and just fill with a solid color, the blurs may not be an issue for you. -crow

Here is a 30p frame we shot recently. Our green screen was not as flatly lit as it could have been with more time, but you play the cards you are dealt... 30p 1/48th sec sthutter speed (reduced from 1/60th) Before: (Note the blurred hand) After: (Note a slight white outline around the blurred hand)

A few more notes... 30p and 24p look a little different when played at 29.97 interlaced. 30p will have a little smoother motion than 24, but some of us like the look of 24p with a 3:2 pulldown. (It looks less "video" like) If you are blending with other 24p elements that have a 3:2 pulldown, then maybe you should shoot 24p. Be aware that motion blur will be more apparent at 30p and 24p, depending on your shutter angle. Your green/blue screen keying software (or hardware) hill be taxed to the limit at those blurred edges, where the green blends with your subject. Once again, a test may be in order. If the green blurs are too difficult to remove, consider a lower shutter angle (Faster shutter speed) to minimize the blur. Shooting at 30p and playing back at 24p has a nice slight slo-mo effect, taking the hard edges off of fast motion. Your dancers would have to dance 20% faster to remain in sync after the speed change, but it is a nice effect. Definitely test this before betting the farm on it... -Crow

We have an SDX900 with an SDI out card. The only thing we use the card for is SDI out to hard drive when we shoot in-studio green/blue screen work. We can run a single cable to a Mac with SDI Input in another room. Other than that we always shoot to tape. We had the advantage of having a DVCPRO50 studio deck before we got the SDX900, I should add. Listen to CB though, if you are using a camera in the league of the 900, you need to have a deck. (How can you shoot hand held sports or music video footage trailing a PA with a laptop? ;-) :P -Scott

We use both DVCPRO50, AVID Meridien/SDI and Digibeta,and you needn't worry about the transfer as long as you use the SDI out of the DVCPRO deck into the D-Beta deck. I've done this often and the results never dissapoint. -crow