View Full Version : Green Screen Advice
David Scattergood May 3rd, 2008, 06:06 AM Hi,
I took a phone call yesterday from a client enquiring about the possibility of me doing some green screen/chroma-key work. As usual I have to get the ball rolling pretty quickly (although I prefer it this way - it's the only way to learn!) and will set up a meeting some time next week.
I suggested I'd look into over the weekend and have set aside time to investigate the realms of this technique (having not promised anything but keen to give it a go).
I have a couple of browsers open from the Ken Stone website with a great deal of helpful tips and techniques, but would love to hear from you folks on here (where to be fair I've amassed most of my related knowledge from :) ).
There were a couple of posts on the JVC boards relating to this subject (which I've read through) but they are a couple of years old (and may have referred to older versions of FCP).
I'm running FCS1 (FCP5, motion et al) alongside the HD100.
I think the key here is budget (possibly on their part as well as my own)....which is as constricted as ever. The footage may end up as clips on websites (it's for a design company) rather than DVD, but until I meet I can't be sure.
I could probably extend to purchasing the cheapest possible muslin (a poster on here has used a roll of graphic paper with apparently decent effects); I'd thought of popping in to either a large, local camera store, ebay, or perhaps a fabric shop. There are a great deal of solutions out there (plug ins; AE etc) but I simply cannot go that route at the moment.
The DVcreators site has a few good tips about lighting (which again is on a budget...might be a case of hiring for a day and using the living room as the 'studio') with advice on a uniform zebra and lighting the subject from above producing a white rim around the subject. Ultimately it will come down to trial and error, but it might be a good opportunity if all goes ok.
Any suggestions would be greatly received.
Thanks.
ps: is there chromakey work on Tim's (soon to be PAL? :) ) tutorial DVD?
Tim Dashwood May 3rd, 2008, 11:10 AM I'm afraid I didn't get into green screen in the volume 1 ProHD DVD. The rules of lighting for green screen apply to all cameras, HD, SD or film, so we might do something for another 'Cinematography Tips DVD' idea we've been batting about.
Here is my #1 tip for green screen work: counteract spill with 'minus green' gels (magenta.) Spill suppression will work to a certain extent in post, but try to get rid of it all on set and you'll be a happy camper. The basic concept is that the opposite colour to green is magenta, so magenta will cancel it out.
To do this turn off your key and fill lights, leave the green screen illuminated, and then rim light/back light your subject with 'minus green' until you see no spill. This is especially important on subjects with blond hair or a bald head.
Here's an example I shot for a client last year. http://www.intervent.ca/programs/ Click on the "90 second educational video" to see the end result. This was shot at 720p30 with an HD100 and the 13x3.5mm lens. I easily composited and keyed everything within Apple Motion 3.
EDIT: Added a behind the scenes photo from that shoot so you can see how it was lit. The BG was lit flat mostly with a motorized Broncolor Cumulite on fill mode and the lower shadow areas filled in with a Rifa softbox. The subject was filled with a Diva Kino, a 150W tungsten Fresnel used for an eye light, keyed with another Rifa (which also spilled onto the green screen) and 150W Fresnels with minus green were used for rimming his head. I would have normally only used one, but the client wanted a second hotspot on the other side of his head for "symmetry." I wasn't totally happy with this but you have to do what the client wants sometimes.
Doug Okamoto May 3rd, 2008, 11:56 AM Tim's sugestion on magenta will work in most situations. I would presume thought that (in this case) a design company would be very particular about the light colors being used. Lighting a greenscreen is very subjective but there are a few "rules."
You probably already know this but the key (no pun intended) is to make sure that you don't light your greenscreen too much and that you light it evenly! We used to use cheap halogen worklights at a very high angle to the camera and that worked very well, most of the green spill hit the floor then. Also, keep your subject about 3 to 4 feet away (or more if necessary) from the greenscreen, that will also reduce the spill. Doing this made it so we didn't have to do very much (if any) color correction in post.
For a fill I usually used a bounce or kept the key very high and the fill low to eliminate shadows on the greenscreen.
Tim Dashwood May 3rd, 2008, 12:24 PM One more tip:
If there is any motion shoot above 1/48th of a second shutter. 1/100th will help minimize motion blur that will just cause you headaches later. You can artificially add motion blur back in after the key is cut.
Jim Andrada May 3rd, 2008, 07:41 PM WOW, I agree with you that the double hot spot looks really strange. Even if it is "symmetric"
David Scattergood May 4th, 2008, 03:10 AM Thanks everyone - I feel much better about this now (almost to the point where I may perhaps pull this off!).
Here's an example I shot for a client last year. http://www.intervent.ca/programs/ Click on the "90 second educational video" to see the end result. This was shot at 720p30 with an HD100 and the 13x3.5mm lens. I easily composited and keyed everything within Apple Motion 3.
This would be perfect and probably what they're after (it won't at all be corporate...maybe even a vanity project/s for some of the key staff - simply people talking in front of the camera, nothing too acrobatic). I couldn't hope to get it spot (again no pun intended!) on like that but I'll try my best with the kit I currently have. Good tip re the Magenta gel and luckily I know of a local firm who supply a range of gels.
You probably already know this but the key (no pun intended) is to make sure that you don't light your greenscreen too much and that you light it evenly! We used to use cheap halogen worklights at a very high angle to the camera and that worked very well, most of the green spill hit the floor then.
I knew hardly anything about green screening before these posts (and a few reads on the internet) Doug, so again thanks for all of the advice.
Interesting to read you used halogens - because here's my [current] plan:
The client mentioned he wanted a quick test to show the team (he's the head of design and they are the folks requesting this project) but suggested I could merely test against my hand (as an example) over a bit of green/blue cloth - now I can imagine this would look 'bobbins', so I'd like to step this up a few gears as much as my budget allows.
Unfortunately I do not currently own any lights (believe me they're up there on my priority list) but would be willing to hire some in. I'll use my living room as a 'studio' and the use of halogens is interesting because directly above the backdrop are halogens - if I could use these to some effect then that would be extremely handy.
Again due to lack of budget, rather than purchasing a ready made frame for the green material I'll nip to the local hardware store and grab some ply in order to construct a (dismountable) frame. I have a ringlet device I can use to hold material taut if need be. Is there any type of suitable material I might be able to use which is pretty much 'green screenable'?
Tempting to look at some of the more costly solutions (the chromatte system with the led rings and glass embedded screen!) but absolutely not an option.
I can position the subject 3/4 feet in front of the screen but the due to the small size of the room the camera lens would have to be fully zoomed out (the camera will be also backed up against the back wall).
I'll shoot in 720p25 (over interlaced) as I'm fairly certain they'll be impressed with the progressive look of this camera.
I've read that you should have the zebra eliminated (a uniform zebra from a 'non hotspot' lit background) via one or two steps down (set zebra at 100%?) then when the subject is positioned then drop the aperture down a further couple of steps (drop from 2 to 4 as an example?).
Might there be any preferred scene files for this type of shoot?
Aside from not using transparent objects in the shot, green (or blue) clothing and over excessive movement, I'm good to go - the lighting is the most worrying part for me.
One more tip:
If there is any motion shoot above 1/48th of a second shutter. 1/100th will help minimize motion blur that will just cause you headaches later. You can artificially add motion blur back in after the key is cut.
I was aiming to shoot 1/50 (as I usually do with 720p25) - interesting mention of artificially adding motion blur - would this be for technical reasons or aesthetic (more filmic look?).
I'm sure I'll have a few questions come post production - I was intending to use FCP (5) rather than motion (v2) - I presumed FCP was the only way to go (if you only had the FCP suite at your disposal)?
Huge thanks for your time answering my questions.
Cheers all.
EDIT:
*This attachment shows where I intend to build the backdrop (directly in front of the brick fireplace/tv panel).*
Brian Luce May 4th, 2008, 04:11 AM Though I was never the guy responsible for lighting, I've been on a lot of greenscreen shoots--always in a controlled studio environment. #1 problem was always spill. We had a cyclorama and full body shots presented even more problems with spill.
The other thing is know your background before lighting the subject. Indoors? Outdoors? Which side it the key light?
Another useful tip would be to avoid using your fireplace for burning wood!
David Scattergood May 4th, 2008, 04:32 AM Though I was never the guy responsible for lighting, I've been on a lot of greenscreen shoots--always in a controlled studio environment. #1 problem was always spill. We had a cyclorama and full body shots presented even more problems with spill.
The other thing is know your background before lighting the subject. Indoors? Outdoors? Which side it the key light?
Another useful tip would be to avoid using your fireplace for burning wood!
I presumed most of the shots will be indoors but outdoors would be handy (using the sun as a good lighting source). Trouble is, in the UK the indoors environment is your friend :)
Has anybody shot green screen outdoors?
I think I'm most worried about green spill - if it's not done well it end's up looking like a dogs dinner.
Yup - there's enough electrics within the fireplace to heat the room off it's own back!
Just spotted this material on ebay (seems like a good price too):
http://cgi.ebay.co.uk/TUFF-PHOTOGRAPHIC-BACKGROUND-CHROMAKEY-GREEN-SCREEN_W0QQitemZ120244943961QQihZ002QQcategoryZ3860QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1 638Q2em118Q2el1247
Cheers.
Dan Parkes May 4th, 2008, 06:18 AM Hi David
I am recently in a similar situation. My client wanted 17 interviews shot against a greenscreen, all to be shot within one day in Birmingham (while I am based in Brighton!). Time and distance meant I wouldn't have much time to set up an elaborate lighting system in their board room. Here was my solution.
I hired the Datavideo Chromakey, which is a dual colour LED ring with a retro-reflective backdrop cloth -this system does not require you to light the backdrop, you only need to light the subject, plus it gives up a perfect key in either blue or green depending on what the subject is wearing. You can see the system I hired here: http://www.hireacamera.com/camcorders/clk100.asp
Some considerations: you need a 82mm-72mm stepdown ring for use with JVC HD cameras. Also, I am presently exploring the use of the After Effects plugin 'Keylight', apparantly used on Harry Potter and other big budget films -you can download a 'rented' version of it that lasts for one day, for only £
1.75 (!) at http://www.thefoundry.co.uk as I have found most of the standard chromakey presets in NLEs are not good enough.
I have a May 10 deadline so will let you know how I get on.
Regards
Dan
David Scattergood May 4th, 2008, 08:01 AM Cheers Dan - aye, I've seen that set up (Chromatte I think - developed by an ex BBC guy). I think there are a few dissenters mind but I couldn't tell you what their niggle with them was. Definitely a consideration however (I'll look into the step down rings, might need these for other lenses also) and perfect for you cross county trip :)
Unfortunately I don't have AE (add that to my wish list!) so I'll have to see how I get on with either FCP or motion.
Let us know how you get on with it Dan.
Cheers.
George Kroonder May 4th, 2008, 10:17 AM I hired the Datavideo Chromakey, which is a dual colour LED ring with a retro-reflective backdrop cloth -this system does not require you to light the backdrop, you only need to light the subject, plus it gives up a perfect key in either blue or green depending on what the subject is wearing.
This is totally alien to me; lighting the talent and backdrop from the camera. I can't see that being a good idea. Also I doubt you get an evenly lit bg. But I'd be interested to know how this works out.
My 'rules' for ck-ing are:
- Light backdrop evenly with soft light, don't overexpose
- Get some distance between talent and backdrop, >> 3 ft.
- Light the talent as required (usually 3 point system)
- Flag lights to prevent spils
You can use green filters on the lights lighting the greenscreen; I've used Lee 138's for this with good results. The Lee 738 is supposed to be even better, but haven't tried it myself.
Depending on how you're shooting the talent, it can get more difficult. Wide shots or dancing is (much) more challenging than talking heads or fairly static medium shots.
Best go somewhere you have some room to work with. Your living room may not be the best choice. Having more room will enable you to control spill by moving the talent further from the backdrop and to choose the best camera position.
Having a good CK-pluging or app. make the work that much easier. I use Primatte Keyer (Red Giant Software) but I've also heard good things about dvMatte (dvgarage.com). Both of these are much better in spill removal then the standard keyer in FCP.
George/
David Scattergood May 4th, 2008, 10:25 AM Best go somewhere you have some room to work with. Your living room may not be the best choice. Having more room will enable you to control spill by moving the talent further from the backdrop and to choose the best camera position.
Thanks George: I'll discuss this with the client next week - perhaps I could use their offices. The initial phase is for me to show some test green screen footage hence the living room. If that comes off *ok* then I guess there's room for me to develop this further.
Is spill really that obvious when you're filming (bearing in mind I've never been on any type of chromakey shoot)?
I think I might initially purchase the muslin green screen cloth I saw on ebay earlier (linkie posted) - for £28 (and apparently pantone colour matched) it's a start for test footage at least - but really it's the lighting I'm more concerned about.
Dan Parkes May 5th, 2008, 05:15 AM This is totally alien to me; lighting the talent and backdrop from the camera. I can't see that being a good idea. Also I doubt you get an evenly lit bg. But I'd be interested to know how this works out.
George/
Sorry George, I think you misunderstand the process. The LED ring does not light the subject at all. It only creates either a solid blue or green background behind the subject, allowing you to focus entirely on lighting just the subject using the usual 3-point system or whatever is required. The clear advantages here of using reflective media as a BG is that even if the BG has creases or crinkles it will not affect it and you can instantly change the BG from green/blue depending on the subject's clothing, plus it saves a lot on setup time.
This technology has been used by many broadcast TV stations for the weather segments for years but is now just becoming available for others. As soon as the system was advertised here in the UK it was instantly sold out and is presently on back order, so I have only been able to hire it.
Brian Luce May 5th, 2008, 09:45 AM This technology has been used by many broadcast TV stations for the weather segments for years but is now just becoming available for others. As soon as the system was advertised here in the UK it was instantly sold out and is presently on back order, so I have only been able to hire it.
I've read reviews of these pricey rigs and was left with the impression they solve many issues with chromakeying but also create new a lot new problems.
George Kroonder May 5th, 2008, 10:58 AM Sorry George, I think you misunderstand the process. The LED ring does not light the subject at all. It only creates either a solid blue or green background behind the subject
Hi Dan,
First I heard of this so forgive my ignorance, but how do you prevent the LED ringlight from lighting the subject as well? It's right there on the lens (as seen on the link you provided).
Sure, the keylight will be much brighter than the LED's, but doesn't this create problems in the shadows?
This technology has been used by many broadcast TV stations for the weather segments for years but is now just becoming available for others. As soon as the system was advertised here in the UK it was instantly sold out and is presently on back order, so I have only been able to hire it.
So good results? What kinds of shots/setups? Can you post screengrabs (LED on/LED off if possible)?
George/
P.S. I'm veering off topic a bit, maybe this calls for a new "Experiences with Datavideo CLK100 Chromakey solution" in Open DV or Photon Management forums?
George Kroonder May 5th, 2008, 11:12 AM The initial phase is for me to show some test green screen footage hence the living room.
You can actually key on just about any color, not just green or blue. As long as you have enough contrast between the subject and an even color, todays keyers will do a good job. Certainly enough for a test.
Is spill really that obvious when you're filming (bearing in mind I've never been on any type of chromakey shoot)?
No, it is often not that obvious on a lit set. There for you should light the background and talent separately i.e. light the bg with talent (or stand-in) present but not lit and light the talent with the bg lighting turned off. That way you can more easily spot spill.
George/
Ben Winter May 5th, 2008, 11:34 AM Hi Dan,
First I heard of this so forgive my ignorance, but how do you prevent the LED ringlight from lighting the subject as well? It's right there on the lens (as seen on the link you provided).
Sure, the keylight will be much brighter than the LED's, but doesn't this create problems in the shadows?
From what I've seen of this system the camera/LED assembly can be a good ways away from the talent and still reflect off the background, so the intensity of the LEDs on the subject is very small while the reflection off the backdrop is still strong.
George Kroonder May 5th, 2008, 11:50 AM Hi Ben,
I'm sure it has it's advantages but isn't the LED ring right on the lens? The bg probably is some highly reflective surface, like the 3M Diamond Grade Reflective Sheeting you may find on traffic signs and sefety gear.
It may be an acceptable 'quick & portable' solution, just can't see it as a good general CK-solution. But I may be completely wrong and I'd love to know more.
George/
Dan Parkes May 5th, 2008, 01:56 PM Hi George
Yes, this is a little off topic, so to keep it on topic I have attached a photo my client took of me and my JVC GYHD201 camera with the LED ring setup... (!)
As Ben has already mentioned, the subject is normally at such a distance that there is little to no green/blue light reflected on them at all. The LED comes with a dimmer so you can control the intesity of the LED if there was an issue with this. I also use Adobe OnLocation as a monitor and use the Vectorscope to monitor any possible spill, and I found the setup created a very good chromakey.
It is also not prohibitively expensive to buy. The basic setup can be purchased here in the UK for £400- 500. Filming corporate interviews in various European countries as I have been recently it would have paid for itself and would have been so much better than lugging extra lights and a large lastolight around!
I will be keying the interviews this week, once I get client approval, but due to its internal nature I am probably not at liberty to share a screengrab, sorry. The client is particularly sensitive about this.
Regards
Dan
Dan Parkes May 5th, 2008, 02:00 PM PS
The only drawback I can state, with the JVC being 82mm, using a stepdown ring does create a vignette if shooting completely wide. However, since I was normally at least several metres from the subject and shooting head and shoulder interviews, I was zoomed in sufficiently to avoid this problem.
Dan
Jim Andrada May 5th, 2008, 03:09 PM Quick question - do reflective items like eyeglasses create a problem?
Dan Parkes May 5th, 2008, 03:14 PM Hi Jim
Yes, this was a concern I initially had. Several interviewees had glasses and I wondered if this might be a problem. But I found that if they are looking to an interviewer off to the side of the camera it was a never an issue, coupled with the fact that the camera is set at a reasonable distance away.
Dan
Claude Mangold May 6th, 2008, 01:24 PM In 2002, when I was still TV producer we tried this system out, with the reflective bg cloth.
It worked beautifully with static subjects.very clean contours, and no spill at all if you can believe this.
Except people's eyes get tired very quickly from the glare - and even TV hosts hated his.
But efficient it was !
With subjects moving about, forget it.
Claude Mangold May 6th, 2008, 01:26 PM OH, sorry, forgot to mention - we used Digibeta then
David Scattergood May 6th, 2008, 02:30 PM As I'm only in the process of testing (and yet to hear exactly what the client might want) I'm building my own green screen kit. I was looking a a few hundred quid at least just for the cloth and the frame.
I earlier today sourced a huge fabric store and chose a fairly representative green (cotton - the muslin were cream/white only meaning I'd have to paint etc) a good size for a cheap price.
I'd also found a guide to making your own frames (from plastic conduit) which enables easy dismantlement and a roller to keep the cloth on (and crease free in transit). I'll let you know how I get on and post a pic :)
Due to the small width of the cloth, I'm having to create a hem down the middle:
might this be a problem for keying later on (I'll try to keep it a clean a line as possible)??
Would it be controversial to use the suggested magenta gel over the halogen/s (which I may have to use a temporary back rim lights)?
Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?
Many thanks.
Jim Andrada May 6th, 2008, 03:32 PM Claude,
one quick question. When you say "moving about" do you mean fairly extensive motion such that you'd have to pan to follow them? Would normal, sort of standing in the same spot, or sitting down and moving normally (ie picking things up, turning slightly to talk to the person next to them etc) work OK?
David Knaggs May 6th, 2008, 04:40 PM Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?
Hi David.
Motion gives a fairly good result. I first use the Bezier Mask Tool (garbage matte) to get rid of any extraneous parts of the frame and leave only those parts of the greenscreen that are very close to the subject. This can help in cases where the greenscreen is unevenly lit.
I then use the Primatte RT keyer, which comes supplied with Motion 3.0.2, for the keying process.
Brian Luce May 6th, 2008, 05:56 PM But efficient it was !
With subjects moving about, forget it.
Dealbreaker!
Mark Silva May 6th, 2008, 06:19 PM Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?
Many thanks.
David, if you own adobe after effects 7 or later it comes with the
Keylight keyer for free.
This plugin is VERY robust and pulls excellent keys even with
straight HDV footage.
I would definitely recommend keying in After Effects or Motion if thats
what you have. I've tested MANY plugins and I have not yet found
one that works well in FCP. The keying is ok, but not great and never
is in my experience. Doing it in a compositing app is really my only option
for good keying even for scenes with someone wearing glasses and getting that transparency just right.
Dan Parkes May 7th, 2008, 02:46 AM In 2002, when I was still TV producer we tried this system out, with the reflective bg cloth.
It worked beautifully with static subjects.very clean contours, and no spill at all if you can believe this.
Except people's eyes get tired very quickly from the glare - and even TV hosts hated his.
But efficient it was !
With subjects moving about, forget it.
Hi Claude
Am very curious as to the difference between static and moving objects using the LED ring technology. I didn't see any difference if the subject was moving or not and cannot see how this would affect the key. But for future reference I would be most interested to know.
Regards
Dan
David Scattergood May 7th, 2008, 02:49 AM Hi David.
Motion gives a fairly good result. I first use the Bezier Mask Tool (garbage matte) to get rid of any extraneous parts of the frame and leave only those parts of the greenscreen that are very close to the subject. This can help in cases where the greenscreen is unevenly lit.
I then use the Primatte RT keyer, which comes supplied with Motion 3.0.2, for the keying process.
Cheers David - I'll give motion a go in that case, although by the sounds of it I'm limited in as much as I have Motion 2 only - is there a likewise keyer (albeit not as proficient) in Motion 2?
David, if you own adobe after effects 7 or later it comes with the
Keylight keyer for free.
This plugin is VERY robust and pulls excellent keys even with
straight HDV footage.
I would definitely recommend keying in After Effects or Motion if thats
what you have. I've tested MANY plugins and I have not yet found
one that works well in FCP. The keying is ok, but not great and never
is in my experience. Doing it in a compositing app is really my only option
for good keying even for scenes with someone wearing glasses and getting that transparency just right.
I seem to be in a minor group of none AE owners on these boards - many things point to owning After Effects! I once toyed with getting Shake, but I feel AE would make for a more practical purchase.
I've also produced good results (mainly title sequences) on Live Type which I was surprised about (initially thinking it was just a huge folder of animated titles)...anyway I'm off on a tangent. Hopefully carry out some tests (not fully lit) later today - hopefully with mistakes made I can work backwards and help eliminate them...screen grabs to come folks :)
Really appreciated your comments.
Brian Luce May 7th, 2008, 03:25 AM Here is my #1 tip for green screen work: counteract spill with 'minus green' gels (magenta.) .
What's a good light to use with the orange gel?
Fresnel?
George Kroonder May 7th, 2008, 04:59 AM Fresnel?
Preferably softboxes, flo's or open face lights. Cycs or anything else that will give you an evenly lit CK-screen.
The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.
George/
David Knaggs May 7th, 2008, 07:55 AM ... by the sounds of it I'm limited in as much as I have Motion 2 only - is there a likewise keyer (albeit not as proficient) in Motion 2?
For all I know, you might even have Primatte RT in your version. Why don't you find out? In your version of Motion, select the "Add Filter" icon and then click "Keying" and you should get a drop-down menu displaying all of the available keyers for your use.
David Scattergood May 7th, 2008, 08:46 AM For all I know, you might even have Primatte RT in your version. Why don't you find out? In your version of Motion, select the "Add Filter" icon and then click "Keying" and you should get a drop-down menu displaying all of the available keyers for your use.
Cheers - as it happens I'm currently dismantling Motion this week (reinstall etc)...over the past few days it has grounded to a halt - absolutely no idea what's wrong with it (have trashed prefs etc). Shame as I was pushing it's boundaries on a couple of projects :(
Once it's back up (hopefully this evening) I'll check it's keying capabilities.
Thanks.
George Kroonder May 7th, 2008, 09:45 AM The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.
Sorry, must have still been asleep... The orange gel you could use on the hairlight to counteract spill, but I've never used this. Using a fresnel for a hairlight makes sense ;-)
The Lee 138 I mentioned in an earlier post is what I blather about in the quoted text, and is used to reduce the red/blue primaries on the bg.
George/
Brian Luce May 7th, 2008, 10:04 AM Preferably softboxes, flo's or open face lights. Cycs or anything else that will give you an evenly lit CK-screen.
The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.
George/
I think you misunderstood, I'm talking about the backlight with the orange gel. Not the light for the green screen. Would a 150 watt fresnel make sense? set up pretty high?
George Kroonder May 7th, 2008, 10:47 AM Hah! I must be psychic or delerious from the heat over here; how else can I answer questions before them being asked?
George/
Bill Mecca May 7th, 2008, 11:50 AM I've just begun working with some green screen, with a variety of results.
I remember seeing the LED ring lights a few years ago at the DV Expo East (which seems to be history) and it was intriguing, but someone correct me if I'm wrong, but it won't work with teleprompters.
Brian Luce May 7th, 2008, 12:35 PM I've just begun working with some green screen, with a variety of results.
I remember seeing the LED ring lights a few years ago at the DV Expo East (which seems to be history) and it was intriguing, but someone correct me if I'm wrong, but it won't work with teleprompters.
That's true.
David Scattergood May 8th, 2008, 07:51 AM You probably already know this but the key (no pun intended) is to make sure that you don't light your greenscreen too much and that you light it evenly! We used to use cheap halogen worklights at a very high angle to the camera and that worked very well, most of the green spill hit the floor then. Also, keep your subject about 3 to 4 feet away (or more if necessary) from the greenscreen, that will also reduce the spill. Doing this made it so we didn't have to do very much (if any) color correction in post.
Going back to a more budgeted affair (as much a the LED ring system look promising) I was picking up some materials in a hardware store a short while ago (for the green screen frame as it happens) and noticed those work lights.
I'm surprised at just how cheap they are - £12 ($24) each.
Bear in mind that I have no lighting rig to call my own and that I'm currently testing possibilities, might I get away with a few of these (and apologies for veering into lighting questions)?
They stock mains voltage (and transformer types) halogens at either 500w or 150w - I'm presuming for a small cost I could use the 150w to light the screen and perhaps one or two 500w as fill and back (unsure as to how I would manage a key light) - I'm assuming gels would work the same with halogen lights?.
I was sowing green cotton sheets last night...at the very least I've learned how to sow!
Bill Mecca May 8th, 2008, 09:48 AM David,
I'm interested in the frame you mentioned. could you share more detail?
I have one of those collpasible/pop-up blue on oneside green on the other at work, just used it this week(still trying to master the green screen thing), but have some green fabric at home and have been trying to devise a support system for it.
if i get chance I will convert one of the videos and post it along with pictures. I still had some spill that I couldn't quite control, but the "client" was very pleased with it. Using Avid xdv 3.5.3
David Scattergood May 8th, 2008, 10:32 AM David,
I'm interested in the frame you mentioned. could you share more detail?
I have one of those collpasible/pop-up blue on oneside green on the other at work, just used it this week(still trying to master the green screen thing), but have some green fabric at home and have been trying to devise a support system for it.
if i get chance I will convert one of the videos and post it along with pictures. I still had some spill that I couldn't quite control, but the "client" was very pleased with it. Using Avid xdv 3.5.3
It's basically conduit and associated 'conduit paraphernalia' i.e. elbows, t 'junctions' and hope for the best!
I'll post the link underneath (it's a US site as it happens) - it's worth a punt and will save some $'s but I can't as yet confirm it's practical use...some of the parts I couldn't get hold of (cross/4way junction - had to screw two elbow joints together in the end) and make sure you use wide enough conduit (anything below 22mm will probably collapse as soon as you add green screen). Also, although it doesn't mention this on the site you might need to keep it around 6 foot and perhaps have a third pole (at a 45 degree angle) to keep it sturdy.
If mine works ok I'll post the pics of it 'in action' so to speak.
linkie:
http://www.stormforcepictures.com/howto-buildamobilegreenscreen.php#extra
...right those worklights...bit of muslin over a frame for a softbox and I'm hopefully good to go :)
Bill Mecca May 8th, 2008, 10:58 AM Thanks for the link, that is kind of what I had in mind. I love PVC!!! LOL
work lights run hot so I would beware of the muslin.
I saw something recently where someone lit the green screen from behind. Don't know how well that would work, but I give them credits for creativity.
I got the video uploaded, no audio. I still have to get the pics off the camera hopefully this afternoon
http://www.youtube.com/watch?v=Mt38ZDMKV4M
It goes on and on without sound, but you can see how it came out. I used some small flourescents to light the screen and even with hot spots it keyed pretty well. I did wind up leaving the overhead lights on in the office, and that may account a bit for my being a tad washed out compared to the background. I had an Arri softbox for a key and used a reflector as the fill, an arri with straw gel for backlight.
David Scattergood May 11th, 2008, 12:23 PM Had a hectic few days sorting out a pretty budgeted lighting set up and making sure the screen was taut and even (tapped in ringlets into the material down both sides so I could 'rope' the cloth).
Took the advice on the photon boards and went the flori route, which so far seem ok. Mains wired 2 twin flori 4' tubes* today as the main screen light and will be using a tripod based flori for fill/key (making sure there is no spill onto the screen).
Never really been keen on this type of light (a real cold and clinical look!) but seems to work ok in this scenario.
The tube lights need to be raised* as they are not quite hitting the top of the green for a full, even look (I'll shoot below this).
*if anyone knows of a suitable tripod/stand solution for these 4' lights I'd be most welcome (can't find any for love nor money...looks like plywood options then :) )
Just about to shoot a minute or two test footage, so here's a couple of snaps of my home made 'kinoflo green screen stage' :)
http://farm3.static.flickr.com/2283/2483078237_8e72acfd57.jpg?v=0
http://farm3.static.flickr.com/2248/2483080871_fe3919785d.jpg?v=0
comments always welcome!
cheers.
Bill Mecca May 12th, 2008, 09:56 AM as for stands, I've used some smaller undercabinet type flourescent fixtures (not sure of the weight of yours) but I used velcro to attach (could use small screws) those spring clips used to hold broom handles in the closet. and then used some old semi working light stands. some broom handles/poles in buckets with concrete for weight could work too, but not look as "pro."
as for the clips, not my original idea, I learned it from Walter Graff's site
click for example page (http://www.bluesky-web.com/broadcastvideoexamples-30bucks.html)
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