WHat on earth do people out there use to light big keying studios?
If you look at some making-ofs of movies you will see the ceiling hanging full of diffused "tube" lamps (spots inside cloth tubes) that provide the necessary ambient illumination. For news productions and similar they use huge wide gate spots and tons of them (in a "small" 10x20m production stage used for local news and afternoon tea shows that I know in our area there's 120 spotlights or so). For screens with limited size like yours some area lights (4x4 lights) placed left and right at a steep angle will usually provide enough ambient light. Generally, though, having enough distance between the screen and the foreground is much more important, as it gives you the freedom to agressively light the BG while at the same time use less light on teh forground and work with a larger overall aperture. This often does miracles in terms of making your screen look more intense...
Yup, like Mylenium says in so many words, the keys to lighting a chroma key background are to:
1) make the light flat and featureless,
2) eliminate hot spots & dark spots and
3) light the background separately from the subject.
The implications here are that:
1) it takes more space than you anticipated to separate the subject from the background,
2) a bigger chroma key background than you may have anticipated and
3) more lighting instruments than you may have anticipated.
It may be moot in the Northern Hemisphere at the moment, but don't overlook the usefulness of Mr. Sun for chroma key lighting. I've used a portable green screen angled to put it in shadow with the subject in front. There is VERY little spill so the subject can be closer, and it's simply a matter of creating a garbage mask and pulling the key.
Thanks for the tips, I am starting to see where I have underestimated the lighting. I thought that a few free standing lights would do the trick, but seeing you say that such a small space needs so much light, well, I definitely need more lights. It comes down again, to the type of bulbs/lights to get. I also made a great discovery today, by testing a small patch of our blue screen - The material we are using has silver flecks in it! Can you believe it. I like to think of myself as getting pretty good at the do's and donts of gree/blue screening, AND the lighting (our green screen is rather small - cause of the character models, and they come out very nicely) - and I never noticed this!
As soon as the light hits the blue screen (11meters X 3 meters) the wave form monitor looks like something created by Particular MIR! and I only see that now - 7 months after we installed it. Anyway, now we will get proper material tomorrow (oh yes, the particular shade of blue absorbs the light so badly, that three reheads (800w) concentrated on "Spot", ON THE SAME SPOT barely raise the IRE above extreme under exposure!
Lessons learned - proper material and much, mush more lighting!
Thanks for your advice too - I agree on the space between the background and the talent - luckily we have a rather large studio, so we will be able to get the right distance between the two. I think the next step will really be to get more lights as well as the correct material. I cant believe the screen we have is so bad - though, in my defense (probably no excuse) today is the very first time we did a test shot against it. we will probably end up (so long) using the red heads to light the background, and our free standing flourescents to light the models. If this fails, then we will group the flourescents to light the background - ambience, and the red heads for the models. I also want to use the sunlight, I find it gets me great shots, the problem is our dolly - as with most things at our studio for now, it is self made, and requires an extremely flat surface, otherwise the shake is horribly visible. We will probably look to making something a bit better soon, but for now, it is make do with what we have (the I.T. world I came from also had the saying..."In the perfect world, with limitless budget we could..."
Thanks for the link - with all the books I have, and all the hours spent online, this is the first time II see this particular page. I will read it in great detail tomorrow at the office - I really appreciate it!
Thanks again guys
I agree on the space between the background and the talent - luckily we have a rather large studio, so we will be able to get the right distance between the two. ...we will probably end up (so long) using the red heads to light the background, and our free standing flourescents to light the models. If this fails, then we will group the flourescents to light the background - ambience, and the red heads for the models.
I also want to use the sunlight, I find it gets me great shots, the problem is our dolly - as with most things at our studio for now, it is self made, and requires an extremely flat surface, otherwise the shake is horribly visible.
I'd use the fluorescents for the chroma key background. They'll be flatter. I'd also get some diffusion material for the red heads to light the subject. You can get REALLY nice, soft light just by bouncing the light off a big, white card.
Beware of color temperature differences if you mix sunlight with yolur lighting instruments.
Bouncy dollies? How big are the wheels?
I'd be tempted to use tires & wheels off a kids' 20-inch bike. I'll bet they're bigger in diameter than what you have now, the tires are built-in shock absorbers is underinflated a bit, and the result would be a smoother dolly. It's worth looking in the want ads for a couple of cheap kids bikes.
Thanks for the idea. Ill speak to the other chaps today - that is one aspect of the project that I thankfully dont work on, and that is the filming "Hardware"! I think he is currently using some sort of skating wheels - ill check it out. I will also chat to him today to see about grouping our flourescents together to make the background lighting units. We have a colour expert coming to the office today to confirm all the new equipment has been colour corrected in the new office next to the studio, so I will check with him as well - just to see if he has experience in lighting and what he can suggest.
I hate to throw a wrench in this discussion but here goes. Lighting, all lighting, the simpler you can make it the better. The more lights you throw at a scene the more potential problems you create. It's all position and intensity. The farther a light source is from an object, like a blue screen, the more even the light. The more distance you can put between your actors and the blue screen the easier it is to separate them from the background. Throwing 5 lamps at the screen may not in and of it's self be bad, but throwing 10 more at the screen won't help.
I have never seen a perfectly even screen shot and I've been shooting and lighting blue screen and green screen shots since 1969. Light your subject the best way that you can and then put just enough light on the blue (or green) screen to give some relatively even light behind the performance area. Invest in a light meter. An Incident Meter. Measure the light.
The biggest mistake people make is putting too much light on the blue screen, filling the performance area with spill, then trying to fix the light on the subject by adding more uncontrolled light to the scene. You should keep the light on the screen at least a stop below skin tone. 6 meters by 3 meters (about 20 feet by 10 feet) could easily be lit with 2 1K floods set at a 45º angle to the screen and about 6 or 7 meters from the screen. That leaves you 3 lights to light your talent. The challenge will be lighting the subject with broad lights like the Red Heads and getting the instruments far enough away from the subject to control the light, control the shadows, and control the spill, keep the light on the subject from spilling onto the screen. If I remember right Red Heads are 800W. With any kind of decent camera and some flags, scrims, and barn doors you should have plenty of light from your 5 instruments. I would not throw your daylight flo's into the scene. It's just more uncontrolled light and it's the wrong color. They may be ok for lighting the screen, but they probably don't have the kind of throw necessary to do a good job. DO NOT mix daylight and tungsten light on your subject. It will be a mess that you don't want to deal with.
I thought I would send a screen shot of the bluescreen I have set up since the discussion.
7x800W 32K red heads, and the WFM barely raises 2 bars - still below halfway mark. Yet, it seems to key relatively well. We then use a further two redheads as keylights for the models. There are some hotspots caused by trhe redheads, but they are out of shot when we shoot this particular ship, so we are not too worried about it for now.
I am wishing I had the budget to flood that side of the studio with light though, but space as well as budget wont allow it. Everyone says that there is no such thing as the perfect keying shot and no such thing as a single click key, so I will do what I can with what we have!
Now I can finally spend some real time learning proper Keying techniques. I can pull a semi-passable key, but I want to focus on edge keying now, and getting the cleanest shots I can!
This particular scene, we did not need the sides lit, and a carefully placed blue board on the ground, allowed for some nice movements.
Here's what I see in that picture:
- Hot spots on the blue screen: so hot that they're much brighter than the subject. The subject's intended to be dark, but that's way too much light, and too much DIRECTIONAL light. I'd say you could cut the number of blue screen instruments in half, and you'll want some heavy diffusion to even out the blue screen lighting. Make the blue screen lighting even all across it. Use dimmers on the blue screen lights if you have them. If you do all that, you may not have to worry about...
- The subject being too close to the background, making heavy blue spill a big problem, which would mean that everything from the subject back should be moved about a meter further away from the blue screen.
To second Dave, put silks or some other heavy diffusion on all the lights you have on the blue screen. Using a dimmer is a good idea or otherwise use scrims to cut down the light. And definitely move both the lights, dolly and subject away from the screen and adjust the direction of the lights so the lighting is much more even. It'll require a bit more noodling, but you should definitely be able to kill those hot spots.
Thank you for the advice. I will investigate different diffusion techniques over the next few days and see what I can come up with. The other two will probably be taking some time off over the Christmas season, so Ill probably use the next few quiet days to get up to speed with the new books I have. I see that Adobe is having a weekly special on E-Books, and I find myself almost unable to resist buying them all - The upshot though, is that Ill have a lot to keep me busy with while the office is quiet!
After taking some footage with the settings above (in the picture) I found that keying is not too bad, except for the far side of the model. We are using the AF101, and it has an incredibly shallow depth of field. The director here like that a lot, and wants to take advantage of the feel it gives to have one extremely sharp point, and the rest nicely blurred. He has built his models to take advantage of this. The problem is trying to key out the blurrry edges. As I said in a previous post, I am pretty ok with basic keying, and feel quite comfortable with it, but now I am going to start learning the more advanced techniques - and I assume there is no better way to learn, than with tricky footage!
I find that simple keying makes the blurred edges extremely chunky and crawly all over - apart form the reading - I know what Ill be doing for the next week or two,.....
Ill get the guys together soon, and we will start by diffusing what we currently have, If there is still issues, we will move the row of lights a bit more back. At this point, we are all comfortable with the fact that we dont really knwo what we are doing, so the noodling around the studio is a given!
Ill send more screenshots when we are done.
Thanks guys, and Ill use this post as a platform to wish everyone the best for the Christmas season - for those going on holiday - have a blast - for those staying at home (and work) - um...have a beer? - and thanks to everyine who has made me feel at home on the forum over the past 7 months
Heres to a new year, new challenges and new solutions!!
We did some more tests yesterday, we moved the red heads to the opposite ends of the support bar from the roof, then made sure they were all on flood, and aimed them at the opposite end of the blue screen. After crossing the beams, we get a nice uniform section in the middle of the screen, large enought o shoot what we were planning.
We are now going to start planning some dolly shots, and since we will have to make use of the entire blue screen space then, we will sit around the table and figure out a lighting strategy for that scenario, based on what we have learned from this one.
We have also started using black card for negatice light on the model, and will be painitng the roof black soon as well.
Ill send another pic through when those steps have been taken!