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Old September 2nd, 2003, 08:24 PM   #1
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Lighting using Flourescent

Can anyone advise me on a problem I had just recently in a room lit entirely by Flourescents. I found that the colour balance on my XL1S kept drifting, I tried it on auto, I tried it using the variosu daylight and internal settings, I tried it on manual and setting the white balance using my trusty white card, but nothing would solve the problem until the flourescents were extinguished and I bought in some external lights ( I was just being lazy not wanting to haul lights up three stories.

Anyway this is an issue I have not experienced before, I am sure it probably has something to do with the frequency of the lights, but does anyone have an explanation, and is it peculiar to the XL1S

Thanks in advance

Steve G
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Old September 2nd, 2003, 09:14 PM   #2
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This lighting is difficult to shoot under---especially the older type of fluorescent lighting. For better color balance, there are 2 types of fluorescent filters available. Heliopan is one company that makes them.
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Old September 2nd, 2003, 10:03 PM   #3
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Steve,

Was your drift periodic ? I had a similar issue when I set the
shutter speed manually. Since I was experimenting, I was switching settings during the event. The Automatic exposure modes eliminated the oscillations at the cost of losing control of the shutter speed.
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Old September 3rd, 2003, 10:16 AM   #4
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Frank, Thanks very much for the advice on filters, I will check them out.

Gints,

Yes the drift was periodic, it was almost as if it was hunting for a balance or level with a five second duration. The camera was on full manual so I will try your suggestion and let you know what happens. Thanks for the advice

Best Regards

Steve G
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Old September 3rd, 2003, 12:57 PM   #5
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WB shifts in (mains fed) fluorescent lights or combinations of fluo and incandescent lightsources can only be minimized by setting an as long as possible shutter time (= max 1/60 or longer). Fluo filters are only solving some specific and unwanted properties of fluo light (non monotonic light spectrum) but don't change the WB shift behaviour.
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Old September 3rd, 2003, 01:52 PM   #6
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Andre,

Thanks for the info, I will also give that a try. I was interested in your comment about the mix of fluo and incandescent lights, as that was the case on this shoot. Is it an issue that the combination could have caused the effect we were seeing ? In any event I now know for sure that it was not a problem with the camera, and in future I will make sure I use my own lights if the problem reoccurs.

Best Regards

Steve G
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Old September 3rd, 2003, 02:26 PM   #7
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Andre,

Yeah, I noticed the periodic shift when I froze the shutter speed at 1/120 or 1/180. Since the periodic shift occured under monster flourescent lights (the kind you see on the ceilings of Home Depot, but they didn't buzz as much) at a sporting event, 1/30 or 1/60 produces blurry stills.
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Old September 3rd, 2003, 02:42 PM   #8
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Indeed Steve combined lighting is generally more prone to give the WB shift problems. To make a long story short (?), remember there are several kinds of mains fed (non electronic balast) fluo's available today. They all generate light pulses at two times the mains freq (=120 pulses/sec in the US). The "warm" ones contain a combination of fluorescent powders which generate a "full" spectrum of colors. Unfortunately their optical persitance (afterglow after the pulse stops) is different for the different colors (powders), so that at short shutter settings the camera can sample periodically different colors in the afterglow period. For this reason, even in some pure fluo lighting ambients WB shift exists. When "cool" fluo's are being used the risk for WB shift is minimal because they contain fewer powders which have better afterglow match( but a worse CRI). Whatever fluo (non electronic ballast) is being used if they are combined with incandescent lightsources there is another problem. When the cam "samples" (for shure at short shutter settings) for a few seconds ( periodicity depends on the freq difference betwween yr cam's framrate and the mains freq) just in between the light pulses from the fluo it only "sees" the incandescent light which doesn't show a pulsed behaviour but has a different color temp. So, your cam "sees" in a peridic way, mostly the fluo and a few seconds later mostly the (warm) incandescent light...Hope this helps a bit.
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Old September 3rd, 2003, 05:52 PM   #9
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Andre,

That is great information, and exactly the situation we had with a mix of lights, and you have explained it in a way that even I can understand - thanks to everyone for their advice and information.

Best Regards

Steve G
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Old November 18th, 2005, 11:22 PM   #10
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Flourescent "cool light" kit.

This looks like a good interview kit to me. Keep in mind that I live in Florida, and the first thing I do when I do an interview is turn off the air conditioner and refridgerator to quiet things down in my living room:

http://cgi.ebay.com/1350-WATT-PRO-DI...QQcmdZViewItem

I would be using this exclusively for talking head style interview lighting.
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Old November 19th, 2005, 07:49 AM   #11
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Looks interesting. I have worked with fluorescents and they work just fine. The new electronic ballasts don't show any flicker and some of the bulbs have good color rendering. What I don't like is that the seller is not posting the Color Rendering Index (CRI) of the bulbs. This is important. Ask him before you buy and don't buy if the CRI is less than 85. Ideally it should be 90 or higher. In fact, I don't think a bulb can be considered a "daylight" bulb unless it is at least 90.

I'm sure you are aware that incandescent bulbs will not mix with these due to the color temperature. You could get your own 3200K bulbs if you want to ever match incandescents. Naturallighting.com carries high CRI compact fluorescents and I'm sure there are many others online as well. That's the advantage of using a fixture with standard screw-mount.

edit: I just found a bulb online that I have used successfully and it is 84 cri and likely the one in those fixtures. It should be fine, but still ask the seler.
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Old November 19th, 2005, 09:54 AM   #12
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I have a dozen or so old "Light Bar's" left from Super 8 days. These will hold screw-in bulbs on a light bar, with dual switches. Switch on two or all four bulbs at a time. Used to use them with the old photo-floods of 500 watts each, so a bar will suppart 2k wattage.

At any rate, I've been putting the '100 watt' daylight spiral flos in them lately. (Although the bulbs are rated at, something like 40 watts, they put out 100).

So with all four bulbs on, I get a cool 400 watts of daylight flo . Looks great. There is no 'reflector' on the bars, so it flies everywhere, but I've got a plan for building one when I get around to it.
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Old November 20th, 2005, 11:42 AM   #13
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I would approach that carefully. Not only do they not list the CRI for those lights, they are also 5100k which is not standard daylight color. They appear to be pretty standard compact flos that you can pick up anywhere.

If you want daylight compact flos then natural lighting is probably a good source. You can get the mounts cheap and put them on your favorite brand of light stand.

Think about the dominant light source where you will do you interviews. Is it office flos? Sunshine? Home incandescents? It makes a big difference if you are mostly doing the interviews with one of these sources.

For example my office, where I do the majority of interviews, uses Dulux flos overhead which have a great 91 cri but a bastard 4100k color temp. I was able to find some little aquarium bulbs for stick up 8 watt flos at home depot with the same 4100k/91CRI so they fit in my tripod bag and they are all I need to light an interview with the overheads on.

If you are going to be in a lot of mixed light situations it would be best to stick with standard 3200k or 5500k color temp lamps and gel to match the environment.

Also think about controlability. Most flos a pretty soft and dont need diffusion. The umbrellas in that kit are going to throw light everywhere. Why do you need them with a flo source? For an interview I would just stick one of those compact flos bulbs close to the subject as a key and maybe some bounce for fill and a practical or sunlight in the background and be done with it.
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Old January 2nd, 2007, 06:41 PM   #14
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Anyone use the Lights of American 500w flourescent worklights?

I have 3, haven't used them much, but now only one works. thought it was the bulb, but swapped them out and they are okay so it seems two of the three have developed some kind of problem in teh internal circuitboard, nothing that is obvious though(loose wire etc)

love these things, daylight balanced, 500W output, use only 65W of power and are cool (temp)

just now that I have a definite video use for them they are kaput. Got them at Walmart a few years back but they don't seem to carry them.
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Old January 3rd, 2007, 08:28 AM   #15
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just wondering if anyone who has used them ran into the same problem and how they worked around it. I have asked EFI if they sell replacement parts, but no answer yet.
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