blue- or greenkey

stijnbarbe · March 5, 2004

hello,

I'm going to shoot a music video in studio soon and we're going to add the skie in post. We'll shoot blue- or greenkey and I would like to know if the special SFX stock made by Kodak is worth the high price. We're finishing on video, I don't know if that's important in my choice of stock.

what would you recommend?

fnx,

stijn

John Pytlak RIP · March 5, 2004

Definitely consider the use of the new Kodak VISION2 films. :) The 5212 and 5217 are especially suited to blue and green screen work, with the 5212 even sharper than the SFX200.

http://www.kodak.com/US/en/motion/products...4.4.4&lc=en

http://www.kodak.com/country/US/en/motion/...techv2_05.shtml

Phil Rhodes · March 5, 2004

Hi,

I'd shoot blue, mainly because it's roughly the same colour as the backdrop you're inserting, making any spill less objectionable. The purpose of green is really for video, which resolves a sharper image in green, or if you have blue elements in the image that will wreck the key.

Phil

stijnbarbe · March 7, 2004

Thank you both for your replies. I'll defenitely try the vision2 7217 because the SFX-shots will intercut great with all the 'normal' shots(shot also on 7217 oir other Vision2 stocks). Also I've contacted my local Kodak-dealer and they want to cut down the price a little for vision2 launch purposes.

The blue key seems the best choice to me too. I hadn't thought of the spill issue, but that really is the best argument not to take green. Is it possible to apply a chroma key in a part of the frame only? Since we'll only be adding the sky in post we only have to key the top half of the frame right?.

stijn.

Phil Rhodes · March 7, 2004

Hi,

I'm not sure quite what you mean. Areas that you want to see your real setting in, you don't fill with blue or green. Areas that you do, you fill with blue or green. If you put the key colour in the top of the frame, you'll see sky there, and whatever was really there in the bottom.

The exception to this is if you have a comparatively large backdrop you want to insert, and only need to have live action in a small area of it. In this case you can place the blue only behind the area you need to key accurately, and produce a "garbage matte," which is a very rough hand-drawn matte which defines a large and usually fairly constant area you want to fill with your new background.

This is much easier to look at than it is to explain - you can google for information I'm sure.

Phil

stijnbarbe · March 8, 2004

well Phil, what I actually meant was that this:

the setting is a yard or camping. since it is now winter in the northern hemisphere we can't really shoot ext. even if we would have great weather the sun doesn't get high enough te get a real summer. so we were planning on adding blue sky and fluffy clouds through means of a bluekey or greenkey.

If I could apply the color key only to that part of the frame where the key surface is visible (top half) I can use greens or blues in the rest of the frame no?

I think I'm gonna go for bluekey, but I don't want to limit the use of blue elsewhere in the frame.

basically what I'm asking is wether After Effects for instance can apply color key in a layer that I can resize and place where I want.

I'm pretty sure it's possible, but I guess I need someone to say "sure man just go for it!" and soothe my insecurity

fnx

Stijn

PS: sorry for crappy english here and there

DanStewart · March 9, 2004

Sure man go for it! :D

The garbage matte principal can be used to cover any part of the frame you don't want the keying to affect (although it is a case of actually masking the keyed layer to only include the relevant area).

The only caveat is to get a nice workable and consistent distance between the key and non-key areas, or you're going to find yourself adjusting curves frame by frame until YOU go bluein the face (or green B) )

Dan