What if you need green (like you are shooting something with blue in it). I would use a cloth for that reason alone. But paint would work fine.

Dave T2

Just DON'T buy *glossy* paint to avoid reflexions. By the way, you probably know there are companies that sell the "exact right" paint for this, ain't you?

And, again, why blue instead of green? First thing that comes to my mind when one goes with bleu: you never intend to shoot somebody wearing a pair of Levi's in front of this, right? Or shoot some "blue-eyed Pamela' close-up" in front of this ...?

Randy, you often ask for advice just to ignore it...

GREEN has better chroma ability within DV
I have tried to walk you thru clean keys in the past and you just don't want to hear about what you need to do differently, lighting it seperately from subject and allow DISTANCE behind the subject, between them/it and the GREEN screen. BACKLIGHT on the subject is crucial. Changing the color of the wall does very little to make your images come out better in the end.

I definately think that had you paid for the training sessions we've had for the past 3 years,you would have remembered them. Also I would not feel so much like I was talkking to a [blue] wall.

All the best of luck in the future.
Gary

I don't know much about chroma since I never use it but having seen and worked on some sets using it, I think blue is too much of a frequently present color in too much many things to use a blue wall in the end...
But why is it better to use green in "video" , which seems to suppose it's not as critical with film (???)...? Colors frequency?

But why is it better to use green in "video"

I prefer to use green myself simply because I run into less costuming problems (true chroma key green is a VERY bright green).
To muddy things up a bit though, here's a segment from Steven Bradford's site:

Red, green and blue channels have all been used, but blue has been favored for several reasons. Blue is the complementary color to flesh tone--since the most common color in most scenes is flesh tone, the opposite color is the logical choice to avoid conflicts. Historically, cameras and film have been most sensitive to blue light, although this is less true today.

Green has it's own advantages, beyond the obvious one of greater flexibility in matting with blue foreground objects. Green paint has greater reflectance than blue paint which can make matting easier. Also, video cameras are usually most sensitive in the green channel, and often have the best resolution and detail in that channel. A disadvantage is that green spill is almost always objectionable and obvious even in small amounts, wheras blue can sometimes slip by unnoticed.

Sometimes (usually) the background color reflects onto the foreground talent creating a slight blue tinge around the edges. This is known as blue spill. It doesn't look nearly as bad as green spill, which one would get from green.

Mike

You summed it up really neatly rs170a, thanks!

I'm going to be pushing my wrestling group to get some green screen fabric (instead of painting a wall, cos we really dont have a suitable area to paint) -- what should I be looking for?

what should I be looking for?

You'll think I'm joking but I'm not. It's digital key green spandex (yes, spandex) and it's available from Rosebrand Fabrics. Pricing is very reasonable.

Mike

You're quite welcome FuTz. In addition to Bradford's site, another good one is http://www.philipwilliams.com/greenscreen.aspx

Mike

it never hurts to get a quart of each and test them both with your camera and editing system. I've had the best success with Vegas and greenscreen - I've pulled some amazing comps off white cycs as well. My Aj-D210 camera (DVCPro but still DV25), worked great with green or blue. I had great keys using Digital Fusion and Ultimatte.

Chroma blur applied before your Chromakey effect will minimize the stepping in many cases around your talent should there be a bit of spill.. always even better to just light evenly and keep spill to a minimum.

mike

Thanks for that, mike! (Note to others - search for it on the site, you'll find it)

So I guess if the fabric is about 7-and-a-bit feet tall (as it seems to be, 92 inches wide?) then you could easily run it vertically to get a full-body shot greenscreened.

Since you seem to have used them before, whats the difference between full and cut price...?

Cut Price: $42.50 per Yard
Full Piece Price: $34.00 per Yard

?

Sorry about the link Jason. For future reference, go to ww.rosebrand.com > Film & Video > Keying Fabrics > 92" Spandex.

It's only cheaper if you buy the full (all 65 yds. of it) roll. Otherwise, you're paying a premium for having them cut you a small piece.

Two more chromakey sites I 'd like to mention are Studio Depot (they sell green & blue screen fabric - not spandex though - and a whole lot of "toys") and Ultimatte. These are the folks that make the reqally high-end gear that none of us can ever afford. What they do have though is a lot of excellent information. From the home page, go Support > Technical Library.

Jason, you mentioned using thiis for your wrestling group. Please expand on this as I have no idea what greenscrren & wrestling have in common.

Finally, for anyone who's interested, I'll repeat an archived post I saved from the rec.video.production newsgroup on building and lighting a greenscreen frame. Hope some of you find it useful.

Mike


The basic PVC frame is 9'x12' But it's expandable to 9'x15'.
I used 1 1/4" Schedule 40 pipe. Anything thinner than schedule 40 is gonna REALLY sag in lengths longer than 6 feet.
Vertically braced (with a 9' pipe, the same dia.) at 6 feet to prevent sag
when stretching the backing material.
Two of the six foot sections have T connectors glued in on one end to accept
the 9' vertical brace.
The 9 foot sides have the corner connectors glued in place on one side.
What you wind up with, is seven pieces total:"
One 9' pipe (Vertical brace pipe);
Two 9' pipes with 90 degree corner connectors glued in top and bottom
(Vertical sides);
Two 6' pipes with T connectors glued in on one end. (One half of Horizontal
top and bottom.);
Two 6' pipes open at both ends (Other half of Horizontal top and bottom).
To make it easier to get apart, I used a heat gun to slightly shrink the
ends of the pipes that aren't glued in place. A T connector was used to
check fit.
It won't fall apart because the fabric holds it all together.
Two Lowel tilt clamps and two C-stands hold it up.

Since I want the flexibility to use two different widths I needed to use an
attaching method that did not involve sewing on Velcro tabs, or installing
grommets.
What I found while roaming around the hardware store was a clip called a
"Crocodile Clip." They are made for tarps and are about a buck a piece.
I needed about 30 of 'em.
Well, they work great. Just clip them over the fabric and set the lock.
The fabric stays in place. Then tie the clip to frame. Once tied on, you
don't have to remove it. Just unlock the clip from the backing. The clip
doesn't harm the backing if you don't try to stretch the backing too far.

I use a black duvetyne backing behind it to block out bleed through back
light. Black plastic sheeting works well too.

Cloth is certainly more handy, but paint, as has been said by others, generally works out better.

Look at this $40 bucket of paint.

If you're feeling daring, take a look at 3M's retro-reflective laminates and paints. You could build your own Reflecmedia-style kit with retro-reflective backgrounds and led-ring illuminators (didn't Play Inc. call this the "Holo Ring?"). With properly applied retro-reflective materials, you can get some very impressive results.

If you'd rather just spend money on the problem, you can buy a kit.

In the absence of ring-illumination trickery, the most critical part of getting a good key is going to be the quality of your lighting. If the best you can manage is a desk-lamp lighting the bottom-corner of your background, you'll need to use more time-consuming methods, like difference-masking.

Jason, you mentioned using thiis for your wrestling group. Please expand on this as I have no idea what greenscrren & wrestling have in common.

Mainly, its for profile / promotional shots - switch on Raw and SmackDown and you'll find "coming up" segments that are basically chromakeys of wrestlers imposed onto some kind of dynamic/moving/wrestling-related background (the best we have at the moment, hilariously, is a black cloth...!)

Hmm no way we could afford 65 yards of that, so I guess the premium price it is... (dang!) hehehehe

Thanks for all the replies. There is one reason why I will use blue paint instead of green:
Vegas 5 (my most favorite program in the whole world) is very strong in many areas but in keying out the green it is not. Yes, lighting is huge factor and distance from subject to screen as well. However, I have read numorous threads that no matter the situation even after using saturated green ect...that there seems to be always a slight green glow around the subjects body. I would way rather have a slight blue glow for it would be far less noticable. I have seen huge Hollywood sets that have no problems using the "blue" but I guess another factor is that if I paint one wall of my office blue it would much better on my eyes then GREEN.

True about Hollywood using blue sets, however this is mostly on film. George Lucas still uses blue even with HD, but most video work, even Hi Def more and more is shot against green. Really depends on your mood though, Total Recall for example shot against an orange background so they could get light reflections resembling the Mars look. So different colors still work aside from blue and green.

mike