DIY Green Screen
 

I'm interested in making a quick green screen for a shoot next week. I was thinking of going to the fabric store and getting the brightest green fabric I can get my hands on. We have pleanty of lighting, and we won't be using the green screen that often, so I don't want to spend a bunch of money on it right now.

My question is, will a seam in the fabric (we'll sew it together) present a problem for keying? It will be pulled tight with lots of light on it. Any suggestions?

I'm doing the same thing myself, bought to pieces of fabric and waiting on my better half to play seamstress. I've done it with a smaller piece of fabric and the only issue was spill,( Iwas sitting far too close to the fabric) the wrinkles etc posed no problem.

I just stopped by the ol' fabric store. I found a blue canvas denim type material that is about as chroma blue as it gets. $1 / yard! This is going to be a nice & cheap little project. I'm hoping the blue will not pose any keying problems. They did have some other green stuff, but it looked nowhere near as god as the blue fabric does, and it was around $7 / yard. They also had some really thin cotton, for $3, but I thought it might have been a bit to thin, plus all the wrinkles and it wasn't nearly as wide.

If you're using fabric, just make sure that you stretch it tight enough to get all the wrinkles out. Your eye may not see shadows, but your camera will. Oh, and here's a trick I learned a long while back:

if you have ANY sort of access to scopes, dv rack, Finalcut on a laptop, ANYTHING with a vectorscope, you'll be able to pull better keys. It's not about having "a LOT of light on the backdrop" its about having EVEN light on the backdrop. If you have too much, it'll reflect back on your subject, and make a dirty key.

Light your backdrop so you feel its even. If you can use a handheld meter, it'll make this process faster. Set up your camera, and frame it so you get as much of the screen as possible, and as little else as possible. On the waveform monitor, look for any dips or spikes where your backdrop is. Once it's all even - a flat line on the waveform - turn on your key light in the foreground and white balance. Next, turn off the key light, and reframe the way you had before. Close your camera's iris all the way. Look at the vectorscope, and open the iris on the camera till you see the green spike on the vectorscope peak. At some point it'll start receding. That's the point you're looking for - the peak on the vectorscope where any farther open or close on the iris makes the peak recede. That's your exposure for maximum saturation. Now when you light the foreground, leave the camera set as is, and light for that stop. If you're worried about bleed from the background, you can light for 1 stop over that max-saturation point.

Here's a tip too - if you light the background with green tubes or green gelled lamps, you can get away using less light on it, and a more open stop on the foreground. It's hard to explain but quickly visible on the vectorscope.

Another cheap DIY greenscreen that works well...

Go to a flooring store and ask about linolium that has been returned, or has a defect on the surface (you want the back anyway) You can often get this free or low cost.

Paint the back side of the linolium with chroma green paint and let dry. You can fasten this to a wall and even allow it to bend onto the floor for a seamless corner. It is stiff, you you don't get the wrinkle problems you get with fabric and it won't flutter if there is air movement near it.

I use Ultra 2 from Serious Magic for all my keying. Combined with DV Rack, you can get some phenomenal keys. I use both a "factory cloth" and cheap green cloth of different shades from the local store (I just bought some thin white material to make a silk for diffusing sunlight also). I like Ultra because you can easily wipe off and bad key spots with their simple tool. Great for eliminating seams and wrinkles.

The cheap green material works well if you follow instructions from the prior posts about lighting. Eveness and control are what you are after (I mount a Lowell Tota with a top and bottom barn door up high on a C stand over the talents head - the barn door keeps light off the talent). I added black material hung on the sides of the area where the talent stood to keep spill light knocked down. Made my edges much sharper. Don't forget a key light from behind for separation (put a low watt light like a Lowell Pro up over the top of the screen and shoot down over the back of the body and just highlighting the hair). Make sure the talent is far enough from the screen so there are no shadows.

I've never tried the green gels, but if you shoot just the green screen before taking your shot, you can boost the green color of the screen with color correction to set the key. Works with Ultra, haven't tried it in my NLE Vegas.

Yeah, lighting is no problem for us - we just typically don't have a use for the screen. We did some trial runs in the shop, using a solid blue canvas type fabric that worked out great. Vegas did a really good job of being able to precisely match the color and key it out, without affecting other colors. We did have to do a bit of blur around the subject, but most everything i have seen, there is a slight blur. It looks great though, couldn't be happier for less than $10.

I'm sure there are lots of ways to do this, but unless you're really strapped I'd suggest buying something specifically designed for the purpose. We use Rose Brand for all our theatrical fabrics here at the Opera Company and they have several products for this.

The best "bang for the buck" is their Poly Cyc fabric which is inherently flame retardant (something important to consider from a safety standpoint as many things from your local fabric store are NOT). The 10 foot wide fabric lists for $14.50 per yard, so you could make a 10' x 12' screen for under $60. You can also choose either digital key green or chroma key blue:

http://www.rosebrand.com/A_Com/showd...ectGroup_ID=22

We used this on a shoot a few months ago and it was great.

Oh! Good job. They carry silks too. Been looking for a source like that.

green screen
 

for me a good choice is Foam Fabric like:

http://www.eefx.com/

for a quick setup You can put the fabric green screen in a wood frame and you can use drawing pins to avoid wrinkle

(sorry for my english....i'm learning it)

bye

Use your zebras to check exposure
 

Set up your camera to cover the lit backdrop. Set your camera zebras on and to a low setting: my camera has 70% and 100%. Open your iris up until the zebras appear. Now you can see what's hot and what's not.

Re: DIY Green Screen
 

There are tons of options for DIY green screens. And you're right that you don't need to spend tons of money to make an excellent green screen studio. For the best results, it's best to make sure the color hues are the same for the entire green screen. You can buy a simple green screen sheet on Amazon or a collapsible green screen panel/stand for under $20.

It's good that you already have all of your lighting, but if you're struggling to set up your DIY green screen + lighting, check out this article for more help: https://valoso.com/blog/diy-green-sc...e-setup-guide/

Good luck!

Re: DIY Green Screen
 

Hey Bobby, welcome to the forum :-)

I would think though that if Kit is still struggling to set up his green screen after 9 years, he never will do it!!

Roger