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Old May 6th, 2005, 12:21 PM   #1
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Lighting a moving car in daytime

I posted this at the end of he ".... moving car at night" thread, but dince it's the exact opposite I decided to start a new thread.

I need to shoot in a moving car during the day. My problem (consumer camcorder Sony HC-85) gets too much backlight in bright areas. The exposure "chokes" down and then it's too dark in darker areas (under trees etc.). I can manually set the exposure settings, but there is still too much contrast between inside and outside. I'm guessing some kind of light source could remedy this, allowing more constant light on the drivers face under all conditions. Is there a cheap 12 volt solution? This is just for an instructional type video - purely as a hobbyist.
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Old May 6th, 2005, 12:29 PM   #2
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The cheapest solution might be neutral density gel on the offending windows.
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Old May 6th, 2005, 02:27 PM   #3
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Rigs I've seen for film shoots actually involve a production truck that towes the vehicle, with HMI's and the camera mounted on the back of the truck (or on the hood, or the door, or both).

Roscoe Scrim or ND film on the windows (sticks with soapy water) in the scene would help. Cheap reflectors.

Always shut the autro-iris off. Expose for the faces.
Plan your shots in shaded, even-lit areas. Time of day, camera angles. These are all things you can control to better your shot.

Anyone else?

Jeff Patnaude
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Old May 6th, 2005, 05:29 PM   #4
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I have gotten away with 4 6v single tube mini flo's (home depot-runs on AAs)
taping 1/4 magenta gel over them to kill the green, and then shooting early morn and evening when its not too bright. An overcast day would probably work as well.
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Old May 7th, 2005, 10:52 PM   #5
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Jason,

Thanks for the reply. I'll look into the "improv" method you've suggested. I'll still look for a cigarette lighter type drop light, at least this won't run out of juice in a car! As for the gels, is this something that could be done in post with color correction or is it simpler to "just do it right" from the start?
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Old May 7th, 2005, 11:34 PM   #6
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I would recommend the gels. 1/4 magenta or also known as quarter minus green.
The flo's are a discontinuous spectrum light containing a green spike. If you subtract the green in post you will subtract the green from the lights as well as green from the ambient light, so when you get the flo's to normal all the ambient will turn magenta, and you don't want that. Its just as much a problem as leaving green in the flo's. Plus youll pull all of your hair out in the bay- then it gets in the machines, and you have to vacuum it up, etc..

Think of it this way, some of the light has green (the flo's) some doesn't (ambient) To control a color correction they need to be the same. Your other option would be to add plus green to the ambient, and that's not practical in your situation. Thats the penalty for using consumer units- If you have the bucks you can rent a 12v Kinoflo car kit in daylight balance, no green spike- and super nifty, but it will probably cost a bit more to rent than buying the little lights and gelling them.

A sheet of the stuff is like 5 bucks from a rental house, and you will have a bunch left over. They might even have a few scraps around they could let you have, if they're cool.

Patrick and Jeff's suggestion on the ND is a good one, and an easy way to help bring the background under control, even with the little flo's. I'm assuming the process trailer is out of the budget. ;)
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Old May 8th, 2005, 09:16 AM   #7
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Hey- I thought you can get different color temp flourescent tubes? Why not just get daylight color temp tubes and save loosing a stop or more by gelling them?

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Old May 8th, 2005, 10:30 AM   #8
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Quote:
Originally Posted by Jeff Patnaude
Hey- I thought you can get different color temp flourescent tubes? Why not just get daylight color temp tubes and save loosing a stop or more by gelling them?

Jeff P
Yes, consumer tubes come in different "flavors" The dominant temp varies by manufacture, but the dominant color temp is not what we are gelling for. We are correcting the spike associated with consumer tubes. Almost all have a green spike, no matter their predominant kelvin temp. A few have magenta mixed in. Quarter - and + green both have a fairly high transmission value, so you dont lose much output.

The little tubes I have referenced read about 9000 degrees on my kelvin meter, and require a 20 cc magenta correction to bring them true. Thats a little more that 1/4 minus green gets you, but close enough.
With the green spike corrected they will match outside daylight quite well, coming in if anything a little cool blue. If the blue needs to be pulled back, it will just warm the background a little, and that doesn't look bad.

You can correct for green spikes at the camera with a "flo filter" (essentially a minus green) but in this situation you would be filtering the green in all the light, and the net result would be the same as trying to color correct without the "flo filter", so that wouldn't work so well.
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Old May 10th, 2005, 05:13 PM   #9
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Jason and Jeff, thanks for the input! Next question: when shooting through the front windshield from a camera mounted on the hood, do I need anything beyond a polarizing filter to cut the glare?
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Old May 10th, 2005, 05:50 PM   #10
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Quote:
Originally Posted by Colin Sato
Jason and Jeff, thanks for the input! Next question: when shooting through the front windshield from a camera mounted on the hood, do I need anything beyond a polarizing filter to cut the glare?

A good stable car mount that A) won't come loose and send your camera flyng, and B) wont screw up the car, and C) mounts solid lock down so it bumps and sways with the car. The most common casualty in all car mount shots is the car.

It helps to use ND filters to open up the aperature and shoot as long a focal length as you can so what the pola doesn't cut is not in the DOF.(But too long shows every jiggle, not usually a problem with a good mount and normal CU at the average hood mount distance.) Keep the sun a right angles to the windshield to let the pola do what it is intended to do. Polas are not effective when shooting with or against light. If you can, get a True Pola (2stop) pola. Totaly worth the extra $ IMO.

If you can light it a little, it helps the subject show up through the windshield,
but be prepared for an overall reduction of contrast. Some newer car windshields have a kind of polarizing film or additive, that will , combined with your cameras pola, at certain angles, phase opposite, and look generally wierd, so check the car. This has only happened once out of a couple dozen car shoots. I think it was a Volkswagen.
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Old May 10th, 2005, 06:19 PM   #11
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While the 90 degree rule for the sun is certainly true, using a pola on reflections like a windshield is a bit of a different application, where the reflections are in a sense already polarized by the angle of the glass (which is why it is so easy to remove them with a polarizing filter. It can be nice to do a partial polarization and keep some of the reflection intact, which can look more real.

Jason, you are right about double polarization--I have seen many instances of a sort of honeycomb effect pop out on the rear window as seen through the windshield.
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Old May 10th, 2005, 08:15 PM   #12
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Well sorry, I should have mentioned that I already have the suction cup mount from filmtools. It's the big 6" pumpstyle cup the the bogen head on it. Not too bad in some of the uses I've done, but if you have it really extended you can get some "wiggle' from the play in the rubber in the suction cup. I have a Tiffen Circular Polarizer on order (along with a Setadicam JR), but its an inexpensive one.

I can already feel the downward spiral on my recreational cash flow starting.........................This all started because I wanted to "play" around with video editing, to do this I need video footage to edit, to get this I need DV cameras, to use this I need tripods, stabilazers, lights etc. When will it end!?
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Old May 11th, 2005, 10:33 AM   #13
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Charles has made a very good point about too much vs too little, and the angle of the winshield in the vertical does get you a lot. Ahh the sweet spot ;)

The end of the road, pun intended is when you begin to find ways for this stuff to pay for its self, and next thing you know, your in business. The best advice I would give to people new to the business end, would be to stop leaving money lying on the table.

Charles, what do you think about a sub forum for the "Business of DV Production"

You can email me since thats getting off topic.
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Old May 11th, 2005, 12:52 PM   #14
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I heard about this car rig, and always wanted to try it. Charle's caution is good advice.

you'll need-
several sand bags
a 4ft (about- plus or minus) Length of 2"x6" wood
several bungie cords.
A hihat for the tripod head

Directions:
lay the sand bags in a row across the car hood. Rest the 2x6 on top of them.
the ends will rest by the front tire wells- use bungies wrapped over the 2x6 ends and hook to the tire wells. the hihat will screw into the 2x6 on the hood in front of the driver or passenger. The tripod head and camera go on that (of course).
Use ND and other suggestions for lighting.

Hope this is helpful.

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Old May 12th, 2005, 03:42 PM   #15
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Lights for shooting moving cars inside....

We shoot moving cars every day at work - but usually inside upto only 40mph. In a crash lab!

We use Phantom V5s from all angles normally at 1000fps and have a little extra light to give a reasonable DOF - approx 1MW of tungsten!!! (You don't stand in the impact area when the lights are on - instant sunburn!)

We paint the cars in matt emulsion to reduce reflections from bodywork, the side windows are usually down so we see dummy trajectories without problems. Windscreens are a problem - and we cannot remove them as they are structural - so the front camera angles are carefully selected.

We generally paint the outside car surfaces a dark colour (dark blue normally) so that we can get sufficient contrast inside (where the light is much less, obviously) Dark trimmed cars (like most German cars seem to be) have been known to be sprayed white inside to help too!

The pit is also pretty impressive - it is about 12' deep, the same wide and nearly 20' long...... and has a roof of 2" thick perspex - which can cope with a 2.5 ton Land Rover jumping up and down on it - literally!

Don't tend to use DVs very often - usually just an XL1 for the pre and post test walk around records.
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