Keying question

J

Joe Media

Active member
Hi,
We've been shooting on chromakey for years and never had any real issues. We just did a shoot on the 300 and it keyed wonderfully. We shot full body testimonials on chroma green shot in AVCI-100 720p 24 with 180 shutter. The issue we did have is with some of the shots where the talent had moved their hands a lot. On those shots, there was blur between the fingers that was next to impossible to key out. The blur created what looked like spill but it wasn't. Is this just an artifact of keying in 24p? I'm assuming that 30p would alleviate this but the client requested 24p. Any pointers on how to get a really clean key at 24? Increase the shutter maybe?
Any input would be greatly appreciated.
Thanks
Joe
 
Be sure your shutter speed is 1/48 for 24PN (or 1/60 for 30PN).
I'm not quite sure but I believe default shutter speed on the 300 is 1/24 for 24PN and 1/30 for 30PN, regardless the 180deg shutter angle.
 
CinemaElectronika said:
Be sure your shutter speed is 1/48 for 24PN (or 1/60 for 30PN).
I'm not quite sure but I believe default shutter speed on the 300 is 1/24 for 24PN and 1/30 for 30PN, regardless the 180deg shutter angle.
Click to expand...
Well that would explain a lot. I was always under the impression 180deg shutter was equivalent to 1/48th. I'll have to take a peek when I get back in the studio.
Thanks for taking the time to comment.
Joe
 
IF you need the 24 FPS you could narrow the shutter angle to something tighter than 180 - like 120 or 90 to kill off motion blur.
I generally shoot green in AVC I 100 30 PN. Why , Because I can and more temporal samples are always better with green screen.
I've also taken to lighting the green with kino divas lamped with kino green bulbs . I've lit a 12x2 green rag with two 2 bulb divas and green bulbs. The wave form of the green screen was flat and thin which is what you want.
 
By the way, I suggest you strongly insist with your client about shooting 30PN. That would certainly alleviate the typical 24p motion blur...
 
You must log in or register to reply here.
Back
Top