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exposing road with car headlights


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#1 Adam Wallensten

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Posted 16 January 2006 - 05:12 PM

Hello!

I'm working on a musicvideo where I want to shoot a road (at night), lit up by the headligths from a driving car. (think Lost Highway intro). It's a no budget thing (or atleast very small) and I only have the film stock that I collected on different other filmprojects. The stock with the highest ISO number is 200 (7217) and 250. I have connections to a rental place where I can borrow lamps.

Will the headlights even expose on such a slow stock, or how much additional light will I have to rig on the car to make the road light up?

I don't need the whole screen lit up, only the places where the lightcones from the headlights touches the road, so the texture can be seen. The side of the road and the sky can be black.

I will appreciate any lighting, rigging, exposing advice on this topic.

Thank you

Adam Wallensten
Denmark

Edited by awallensten, 16 January 2006 - 05:13 PM.

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#2 dudeguy37

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Posted 16 January 2006 - 05:22 PM

What about shooting it during magic hour and using the brights, than tweaking everything in post so that the headlights will still be the brightest things in the frame but everything else will have exposed on the film speed you have. Maybe that'll work.
Peace,

-Harry
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#3 Stuart Brereton

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Posted 16 January 2006 - 06:21 PM

What lenses do you have available to you? Car headlamps are PAR designs and have a considerable output in the centre of their beam. Take your lightmeter out one evening and meter them. With 200T and some fast lenses you should be OK, particularly if you're not bothered about seeing too much outside the beams. If you can, overexpose your stock. A night shoot with only black tarmac (or blacktop) illuminated will cause you problems if you decide to 'print up' for any reason.
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#4 Adam Wallensten

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Posted 16 January 2006 - 06:47 PM

If you can, overexpose your stock. A night shoot with only black tarmac (or blacktop) illuminated will cause you problems if you decide to 'print up' for any reason.



thanks for the advice. Why should I overexpose the stock?

My lens goes down to F 1,9 but from what I've heard don't work at their best on their minimum and maximum f-stops. Would it be a good idea to stick to 2,8 or higher. I guess the depth of field will be very narrow, too narrow?

adam wallensten
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#5 Stuart Brereton

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Posted 17 January 2006 - 05:45 AM

If you're shooting at night, where most of your frame is in darkness and the only thing which is lit is the road surface (which is probably dark grey) then all of your scene information is exposing on the toe of the characteristic curve of the stock.

This means that you are exposing only the biggest grains in the film. If you decide to 'print up' to lighten the dark area a little, you will just increase the grain in the picture.

By overexposing, you are placing the scene info much higher up the curve. This means that you will have additional shadow information, and less grain. When you get to telecine, you just 'print down' to however dark you want it.

Lenses are often not their best wide open. Contrast and apparent sharpness can suffer. In this instance that's probably not too much of an issue as your subject (the road) will be moving past camera at some speed, and any slight lack in sharpness will be hidden in the motion blur.
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#6 Brian Drysdale

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Posted 17 January 2006 - 07:17 AM

thanks for the advice. Why should I overexpose the stock?

My lens goes down to F 1,9 but from what I've heard don't work at their best on their minimum and maximum f-stops. Would it be a good idea to stick to 2,8 or higher. I guess the depth of field will be very narrow, too narrow?

adam wallensten


I've done the car headlights during the magic hour trick a few times. It seems to work best the closer to you get to darkness, however, you can't print up for the reasons already given. If you over expose at least you have an option of printing down, it depends on how bright your headlights are and how the road surface is reading.

The best time to shoot depends on the sky. Dark clouds in the background sky and a clearer sky over the subject can help lift the foreground slightly. However, you need to be careful in making a judgement call on when it's getting too dark - the light meter usually says there's nothing there.

At 200 ASA I'd normally use a T1.3 lens, however, since you only have the F1.9 I'd shoot wide open unless you know this particular lens is soft at this stop. It's nice to get the lens stopped down, but sometimes these things are trade offs. If it's a modern prime lens, it should be ok; an older zoom lens you'll need to check it.

Alternative would be to use 500 ASA stock if you want to stop down.
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#7 Stuart Brereton

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Posted 17 January 2006 - 08:47 AM

If you're struggling for exposure, and there is no movement in the frame other than the road, you could of course shoot at 12fps and drive half as fast. You may even get away with 6fps.
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