 Kitty Cross |
Mercury vapour lights and correction Evening all! I've been messing round with some night photography and there's a location down by the boardwalk where a very cool looking oak tree is lit with a mercury vapour street lamp. It's sort of back lit by a fairly intense pinkish glow from the city lights across the bay. It's an awkward lighting situation. Anyone know how to correct for the street lamp? I'd actually like to include the fixture because of the olde world feel of it. As always, I'm shooting film and I will of course bracket, but the filter thing is confusing me. Will the one you use for flourescents correct the temperature? Is there a way to properly expose the shot without having the fixture appear burned?
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Mark Feldstein |
Greetings Kitty. I'll answer the second part of your question first. No, if the lights you're referring to are high intensity mercury or sodium vapor, a flourescent correction filter, like an FLD (usued for daylight films shot under flourescent light) or FLB (tungsten film under flourescent light) won't be of much help to you. Those are considered light balancing filters not color correction filters (cc's), per se. You said the lights have a pinkish cast. That indicates they're warmer lights, probably high pressure and not Deluxe White Mercury or Clear Mercury vapor lamps. So, I'll assume you'll be shooting on daylight film and I'll offer you cc's for color negative and daylight transparency films under like a General Electric Multivapor lamp or their Lucolux variety. These are ballpark corrections. If you're really looking for a pure white from these fixtures, you'll have to experiment OR you can call the street light maintenance dept and ask them what lights they're putting in lately. Sometimes it requires a call to the local utility co. street light division. So.......... For GE Lucalox Transparency Film, e.g., Ektachrome Daylight balanced: Multi Vapors: Lucolux: Now, one of the problems with these correction filters is that if there are other colors in the scene, they'll cause a shift in them. So, whether to filter or not is, of course, a pretty subjective determination on your part. Unless you're concerned with getting some pretty scary results without filtration, I just let them go and fall where they will on the color temp. scale. Using tungsten balanced transparency stock, my preference for that is Fuji, 160 ISO, you'll get some correction built-into the film. GE Multi-vapor As for bracketing, that won't help much with color correcting because all you'll do is darken or lighten a color shifted image. Bracketing, however is of course useful in nailing the general exposure. Remember, these are basically starting point corrections, and may not work to produce exactly what you're looking for. The only absolute way to do that is using a color temperature meter (very pricey) and having a complete set of cc filters. (For those, you may need to second mortgage your home). Depending on where you live, you might be able to rent that kind of meter and a set of cc's. I'll bet your next question is where to get inexpensive cc filters... If so, Kodak makes gel color correction filters and sells them in packets of a few each that insert into various holders that you can rig on the front of your lens. One other thing: If you're shooting color negative film and need a correction for the entire image, a good printer can pretty much find the right color pack to use to do that but it really helps to tell them either what kind of light you're trying to correct for AND even better, have a couple of frames taken with a color checker card, like the one made by Macbeth (available from camera stores like B&H. Hope I haven't confused you more than I've helped. ;>) Take it light.
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Kitty Cross |
Mark thanks for that. I work in the technical end of the entertainment industry so I expect the cc gel you refer to is available to me. (I'm an audio engineer and know virtually nothing about lights which is why I need your help) I didn't make myself clear about the lighting situation. The pink glow is backlight on the tree. Or more precicely in the sky behind the tree. The key from the front is a merc vapour (or something like it as you say)and the cast from the front is kind of a harsh white--a bit blue. I'll have a look for the gel you suggest--any idea of the Rosco numbers? Thanks again for your help. Yes it will be most likely daylight balanced negative film. cheers
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Mark Feldstein |
In that case Kit, ask one of the lighting techs or the camera person what correction they're using which will probably be to tungsten rather than daylight film stock. Rosco gels usually have names and mired equivalents attached to them. Mark
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Pete H |
Hello Kitty, Without all the tech mumbo jumbo..Go to a issue of astronomy magazine or Sky & Telescope..There you will find many filters to take care of the problem of Sodium Vapor, Mercury etc.... Caution: Some of the filters are very expensive as they are exclusively for telescopes. I shoot long exposure shots of galaxy's..and these filters are a must. Pete
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Mark Feldstein |
Wellllll, the problem with what Pete is suggesting is that it's a pretty pricey solution, especially when you consider that you don't even know exactly what kind of lights you're shooting and trying to correct for. If you contact Rosco, btw, they'll send you a swatch book of all their gels. Free too. :>)
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Kitty Cross |
Thanks Pete. I bet I have several copies of Sky and Telescope lying around. Worth a look since some of those things are geared to backyard astronomers. Mark--once again thanks. I think I have an old Rosco swatch book in one of my toolboxes---lighting guys leave so much stuff lying around--I own 3 c-wrenches..... Just need to see if I can relate your numbers to the rosco info. And I can always ask one of the squints. Thanks gents!
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Pete H |
Well Mark, I am a believer in the Apollo moon program philosophy..."Throw enough money at a problem and it disappears" LOL....Just kidding... ..but you're right, some of the filters for astronomical use are quite expensive indeed! :) Pete
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Mark Feldstein |
And also Pete, remember that the greatest scientific advances were discovered through mistake. Of course, the larger the grant money and the greater the funding, the longer it takes to make the mistake. ;>)) Mark
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