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Author
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Topic: Lens Filters
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Galaven
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posted 10-25-1999 07:38 AM
I've watched almost every "Making of" of every movie I have and ive noticed one thing. When they are explaining the effect its always BRIGHTER than the final shot. How is this done? I've heard someone mention lens filters, Is this it or is it something else?------------------
Forget the Past
Live the Moment
Think the Future |
MoCo
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posted 10-25-1999 11:04 AM
I'm not 100% sure what you mean but don't forget that the final shot was Tk'd and color corrected to match the complete film. Also the interviews and observational footage would be shot on a different format (obviously) and therefore would be set for a different exposure depending on what the point of interest is. |
doom1701
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posted 10-25-1999 11:10 AM
And just to add my two cents worth... From personal experience, it's always best to light your set a LOT brighter than you need, and either 1. Use a lens filter (probably not the best solution, but you did mention it), 2. Correct in post (bad idea, but I've had to do it), or 3. Set the exposure on the camera properly (ding ding ding-we have a winner).There is one experience that comes to mind in which I wish to God I had an exposure control on the camera. My set was actually too bright (a room with a lot of windows, on possibly the best day of the past summer). In the shots where I got the auto-exposure to work correctly (based on the light on my characters), the picture was beautiful. If I moved the camera, though, and got one of the windows in the picture, the AE would go nuts, and all the sudden my characters were black silhoettes (sp?). I guess that was kind of a tangent, but you get the idea. Exposure is critical! ------------------
TL
daa Productions Nobody lives forever, so you might as well go out with a good caffeine buzz... There's always hope, because it's the one thing that they haven't figured out how to kill yet... |
Big Al
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posted 10-25-1999 12:05 PM
That is why the DP (director of photography) gets the big bucks. Part of being a good DP is knowing how the film will respond to the light. That light meter that he carries around can also be used to determine a measure of light called FOOTCANDLES, which is, basically, a measure of the strength of light at a certain distance from the light source. A good cinematographer will know that his film has a certain latitude (what range it will give an acceptable exposure in) as well as how to read the exposure off the exposure meter. The set will appear, from the video camera shooting the "making of" video, to be incredibly bright, but the DP will know that if he exposes for the lead actor's face, using a relected light meter, minus, say, half a stop because the actor is caucasian, he knows that the area around the actor, which appears to be bright to the video camera, is actually lit with a mottled light pattern that is only about a third as strong as the light on the actor's face. On film, this will be way more apparent than it is on the video. |
Galaven
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posted 10-25-1999 02:47 PM
Ouch, I understood maybe a third of that.
Im fairly new at the movie thing. I know a bit here and there but could you explain that to me in laymans terms?
Thanks ------------------
Forget the Past
Live the Moment
Think the Future [This message has been edited by Galaven (edited 10-25-1999).] |
Critter
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posted 10-25-1999 06:22 PM
Basicly what Big Al said is that film needs a different amount of light most of the time. It will depend on what is in the shot, what type of lens is on the camera, how much depth of feild is wanted, and several other things. If you see something shot on video, using automatic exposure, it will look much briter than the film version of the same thing. A good book to find is 'American Cinematographer Manual'. It will give more information that you can use for lighting than most poeple will ever need.The copy I have is the 4th edition, printed in 1973. You can try to get one from the American Society of Cinematographers. Light is a strange thing when it comes to cameras. It can do things you would not believe. The different film stocks are made to take advantage of the way light acts in a camera.Rex Winfrey
Critter Creation Shop |
thedude
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posted 10-25-1999 08:40 PM
The lens cap counts as a filter and it darkens the film. :-) |
Galaven
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posted 10-26-1999 06:57 AM
Im not sure I understood that 
Let me tell you my situation and then maybe you can help me.
Im soon going to shoot a desert scene and im afraid that the picture will come out really bright and my actors will be darkend. Its enough that my actors are going to be hot, they dont need to be dark as well. ------------------
Forget the Past
Live the Moment
Think the Future |
Dale Jenner
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posted 10-26-1999 07:25 AM
Go to your local camera shop, make sure its someone who knows what they are talking about eg. someone who has been around a long time, and ask for their advice. Explain your problem and a tip, find out the diameter of your lens before you go, there should be written on it Ø=** and whatever the diameter is.Dale Jenner |
Critter
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posted 10-26-1999 09:11 AM
Sounds like you will want a polorizor (I know my spelling is bad), and a couple of neutral density filters. The polorizor will cut down glare, and the ND filters will allow you to change the way the image looks. If you are shooting on video, take a monitor. Even if you are just using a little walkman size lcd tv. It will let you get a better idea of what the sceen will look like. If you can, pick up a little color tv that runs off 12 volts. They usually don't cost too much, and will help out more than you think. You can use it to check your framing, make sure the boom is out of the shot, and check focus, as well as the color balnce, and brightness. The filters for the camera will allow you to cut the glare you will probably get, and adjust the contrast some with the ND's.------------------
Rex Winfrey
Critter Creation Shop
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Galaven
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posted 10-26-1999 10:32 AM
What is a Neutral Density filter?
Where can I get them?
How much would it cost?
Sorry, Im just new------------------
Forget the Past
Live the Moment
Think the Future |
Big Al
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posted 10-26-1999 11:26 AM
i suppose the really big question is what kind of camera are you using? Film or video? If it is a video camera, does is have a manual overide for the autoiris? If not, you're going to have to fight for your shot.
The autoiris works a lot like a light meter in that it gives you an average exposure for the entire scene, only with a light meter, you have the opportunity to take the info, and translate it into a useful F-stop. (i.e. the meter says F5.6, but there's a lot of sparkly white sand, which is much brighter than the color of an 18% grey card, and my characters are somewhat ruddy from the sunburn makeup, so I'll open it up to expose for their faces a half stop, maybe just above F4)
The video camera can't do this, it just assumes that the brighter sand is only as reflective as an 18% grey card (Ask for it at your camera store) so the sand is exposed correctly, everything else is washed out. Critter's suggestion to take a monitor is right on the money, and is exactly what the professionals do (albeit with all sorts of velcro and vinyl glare hoods strapped all over it, to cut down on ambient light)In addition, there are other ways to help maximize success. One would be to avoid having your subject backlit. Another would be to take some reflecters to provide some fill in the heavy shadows on their faces in closer shots. these can be as simple as a couple pieces of foam core that have been spray painted silver on one side, and the other side left white. Bounce the sun off either side to fill the shadows; the white side will produce a rather soft fill, the silver side a rather hard fill light. Funny this should come up, on the SciFi channel yesterday, the old Star Trek episode "Arena" (Kirk vs Gorn) was on, featuring location work at Vasquez rocks. Hey, these guys had 4 shadows each!!! 4 suns? Not bloody likely. The really obvious thing was when the wind would obviously kick up, the reflectors would start to wobble, and you could see the dancing reflections on some of the rock outcroppings behind the characters.
Also, many video cameras have a "backlight compensation" button, that overides the manual iris by about another stop. this could be helpful as well. |
Galaven
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posted 10-27-1999 07:13 AM
Im using a video camera, not film. It does have an override for the autoiris but its not like you sayed (with f-stops).
But I still want to know how much would a polerizer cost.------------------
Forget the Past
Live the Moment
Think the Future |
EricM
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posted 10-27-1999 06:54 PM
If all you are concered about is getting a usable image, then I don't think you will need any filters. It just sounds like you're worried about your actors being too dark to see.
This should be no problem outside in the desert. The sand should relfect enough light back onto your actors to fill in any harsh shadows.
To play it safe, zoom in on a person's face and set the iris to an exposure you like. Then lock the iris. Now you can zoom out and not worry that something like a bright sky will change the exposure in a way you don't want it to.
If you find that you have too much light, you can increase the shutter speed. This will reduce the exposure further. | |
