color temperature question

[super8er]

wal-mart sells "daylight" flourecent bulbs that are supposedly rated for 6400k. i was wondering how this might look on a film balanced for 5500k(ektachrome 100d) would it look too blue? i remember reading somwere that outdoors light actualy ranges from somthing like 4800k to 6400k and that 5500k is just average daylight. so if this is true i gues it would look ok(right?) :? i bought the bulbs (i figured i minus well, they were really cheap) and the light looks kind of blue next to daylight. anyway, can anybody tell me if the color balance with these will look good or not? responces are much appreciated.

[Super8rules]

You have to be careful with flourecents. They'll give you all sorts of funking hues, usually green.

Remember, flourecents are actually lit gases, so you are not getting a pure color, unlike tugstens that burn filaments, producing strong, constant colors and temps.

I personally would stay away from them, then again, give them a try. You might discover a look that you like.

[Blin]

You'll probably get flicker with most super 8 cameras.

[super8er]

ok,thanks for the help. but i think ill give them a chance. maybe like a 5 second segment or somthing like that. ther light actually looks very even and nice when illuminating my clay animation set. really seems to bring out the true colors in everything. whites look white,reds look red,and it looks good on my dv camera set to fixed daylight white balance.of course it will probaly look alot different on film, but i figure its worth a shot.

[mattias]

check the cri (color rendering index). if it's over 80 it will look fine, if maybe a little green which you can easily cc out in telecine. if it's over 95 it's as pure as a professional flo or hmi.

as for fluorescents being lit gases, that's true but still not. the "lit gas" puts out invisible light which hits the fluorescent material on the outside of the tube, which then glows (fluorescents) with visible light. the mix of materials define how true the spectrum gets.

sodium and mercury vapour lights are lit gases in the true sense, thus they have even more partial spectrums. a low pressure sodium light only has a single spike, which is why red objects turn dark grey. there simply is no red component at all in the light, thus nothing that can be reflected off a red surface.

/matt

[super8er]

so this would be perfect http://cgi.ebay.com/Full-Spectrum-5500K ... dZViewItem unfourtunetly im not that wealthy the bulbs i got from walmart do not say what cri they have.they were the only bulbs there to even have a color temperature rating. im kind of pissed of right now too because ge used to make 5500k photofloods,but now the only thing i can find on there site are 4800k bulbs . would these look good?

[super8er]

ok, i found a pdf file on ge's sight that says the bulbs i bought are 82 cri .so ill definetly be using them thanks for the help everybody.

[thebrowniecameraguy]

You might have to worry about flicker. The movement of burning gas will run 60 cylces a second because of the AC outlights wired to them. I think you may balance it a bit with some incandescant lights pointed towards your set, if possible.

Sometimes you can tell if a florescent tube is about to go out if you flicker your eyes fast enough. If you can see the dark points during that then the bulb is nearing expiration. Also, if you can't avoid using them, add a warming filter even if using a daylight balanced film. This will help to avoid a minimally washed out scene.

I tried this with Kodachrome 25 about 6 years ago. I filmed my church youth group in our youth room that had 3 sets of 4 florescent light strips. Without thinking or understanding the difference between light sources and the daylight balanced film I also brought along a set of bar lites. 4 300 watt tungsten camera lights plus the flors. created a real even lighting situation. No shadows or dark spots, very warm browns and reds with very white whites.

However, every once in a while I would point toward the ceiling when my friends did a little weird jump thing. When the camera was pointed close to the flor. lights it washed out the scene and the bar lites couldn't compensate.

Experiment a bit and have fun!

Cheers,
Jordan

[mattias]

The movement of burning gas will run 60 cylces a second because of the AC outlights wired to them.

120 actually, or 100 in the 50hz world. the gas doesn't care which direction the current is flowing. might seem like splitting hairs but it's actually very importand to determine safe speeds.

/matt

[mattias]

something that is purely academic but still potentially interesting to know is that there's no burning taking place either. the energy put into the gas through electricity excites the electrons, and when they fall back to their normal state a pulse of light is emitted. no chemical reaction at all.

/matt

[thebrowniecameraguy]

I remember trying to learn this for a tech theatre class and I still don't have it right. 120 is correct, but there was something lamp related that we had to designate between 60 and 120 but I can't remember. No its not splitting hairs Mattais! I like to be corrected, it helps!

Jordan

[vidwerk]

Just came back from home depot. They have 24" GE "Daylight" tubes rated at a CRI of 92. I also saw plug-in(non hard wired) fixtures for them that claimed to be low-hum/flicker-free. Are these flicker free for motion picture use? I imagine not. The total for both the tube and fixture is about $40. CDN.

vidwerk.

[MovieStuff]

something that is purely academic but still potentially interesting to know is that there's no burning taking place either.

Yeah, that's always struck me as weird but true.

Hey, here's something that combines standing waves and something burning in a tube. Some of you may have seen it before:

http://www.break.com/index/rubens_tube_expierment.html

Roger

[reflex]

Hey, here's something that combines standing waves and something burning in a tube....

Brilliant. Am I the only one with the urge to try this at home? I doubt my wife would let me live long once she found out how I burnt the house down.

[Justin Lovell]

Just came back from home depot. They have 24" GE "Daylight" tubes rated at a CRI of 92. I also saw plug-in(non hard wired) fixtures for them that claimed to be low-hum/flicker-free. Are these flicker free for motion picture use? I imagine not. The total for both the tube and fixture is about $40. CDN.

vidwerk.

I was checking that out a few weeks ago. Bulbs seem pretty good, and you can even buy plastic housing for the bulbs so they won't shatter everywhere.

I'm also curious if there will be flicker issues. I guess it is also dependent upon the camera you are using. The 1014's 150/220 shutter angle will have different safe speeds than using the 4008's 1/90th or 1/45th shutter speeds.