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Avoidin the green tint in Kinoflows !!!


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#1 Subhash Sukumaran

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Posted 16 August 2007 - 07:13 AM

I recently used a Tungsten Kinoflow for my shoot .. unfortunately there was a mild green tint in it which i couldnt notice wit my naked eye ...
I didnt ve a colour temperature meter wit me either to check before i shot ... Is it adviceable to use a minus green in any case .... Cause most of the kinloflows (Daylight & Tungsten) i ve used ve a green tint in it !!!
First of all y do v get the green tint ?? Y not a blue tint or a red tint ?? (i know this question is kinda stupid but i'd like to know ) :rolleyes:
how do i avoid this situation without a colour temperature meter ???
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#2 Jonathan Bowerbank

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Posted 16 August 2007 - 11:58 AM

I've never experienced a greenspike, so long as I've used Kinoflo lamps? Are you sure you're using the right lamps with your Kinoflo? Maybe the place where you got it went cheap and just got some regular overhead fluorescent lamps.

Here are what should be in them:
http://www.filmtools...iflosacola.html

I'm not sure, do Kinoflo lamps develop a greenspike over time?

Edited by Jonathan Bowerbank, 16 August 2007 - 11:59 AM.

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#3 John Sprung

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Posted 16 August 2007 - 12:13 PM

The green spike is green rather than red or blue because it comes from the physics of the mercury atom. Mercury produces strong UV which is what makes the phosphors glow, but along with that comes a fairly substantial amount of green. I don't know about the green increasing over time, but it could be that the phosphors degrade and reduce their output, making the constant green a bigger proportion of the light.



-- J.S.
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#4 robert duke

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Posted 16 August 2007 - 02:59 PM

[quote name='John Sprung' date='Aug 16 2007, 12:13 PM' post='188296']
The green spike is green rather than red or blue because it comes from the physics of the mercury atom. Mercury produces strong UV which is what makes the phosphors glow, but along with that comes a fairly substantial amount of green. I don't know about the green increasing over time, but it could be that the phosphors degrade and reduce their output, making the constant green a bigger proportion of the light.
-- J.S.
[/quote

heat can cause kino tubes to show a green spike. EIther the enviroment temperature or wrapping the gels around the tube restricting the air flow can cause a green spike. Even closing the barndoors in too much can cause the green to come out.

Poor power can also cause the green spike to come out. It could have been a low or high power that caused the green spike.

It could be a ballast issue. a damaged ballast can put a green spike out.

A colormeter is always a good idea when dealing with non tungsten sources. Hmi's change with age, dimming, and power. flouro's change for similar reasons.
always carry one.

you should be able to colortime out the green spike. Its amazing the ability of colortiming these days.
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#5 John Sprung

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Posted 16 August 2007 - 07:08 PM

A color temperature meter is really only valid for things that have a Planckian distribution of energy, like sunlight and tungsten lamps.

For a much cheaper way to see if you have a green spike, all you really need is a junk DVD or CD. Use it to diffract the light out into individual wavelengths, just like a prism does. Look at an incandescent, you'll get a smooth spread from red to blue-violet. But look at an ordinary flourescent, and you'll have dark gaps and a green spike. Keep one in your meter kit.



-- J.S.
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#6 Paul Bruening

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Posted 16 August 2007 - 08:44 PM

My God, John. That's brilliant.
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#7 Subhash Sukumaran

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Posted 17 August 2007 - 02:38 AM

A color temperature meter is really only valid for things that have a Planckian distribution of energy, like sunlight and tungsten lamps.

For a much cheaper way to see if you have a green spike, all you really need is a junk DVD or CD. Use it to diffract the light out into individual wavelengths, just like a prism does. Look at an incandescent, you'll get a smooth spread from red to blue-violet. But look at an ordinary flourescent, and you'll have dark gaps and a green spike. Keep one in your meter kit.
-- J.S.




now thats some information i didnt know ... using a junk dvd to check the colour temp .. i'll ve to try it out ... usefull info ...thanks a lot .. i understood the mercury atom concept ... but i ve also noticed a blue-voiletish tint in a few HMI's ...is it because of the ballast or the current supply ..
I thought its basically cause of the current supply ..

and i also want to know the fact behind y a HMI starts of voiletish then turns green and then in turn ultimately becomes pure white ( daylight ) ...
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#8 Subhash Sukumaran

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Posted 17 August 2007 - 02:46 AM

Thanks a lot for the information robert ... I've considered a few of the problems that u ve mentioned .. well now i'll atleast know the different options where the problem can start ..

the more CC Gels i use the lesser becomes the intensity ... Vr given only minimum lights for our shoots .. again that becomes a problem ..

Edited by Subhash Sukumaran, 17 August 2007 - 02:48 AM.

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#9 Subhash Sukumaran

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Posted 17 August 2007 - 02:52 AM

I've never experienced a greenspike, so long as I've used Kinoflo lamps? Are you sure you're using the right lamps with your Kinoflo? Maybe the place where you got it went cheap and just got some regular overhead fluorescent lamps.

Here are what should be in them:
http://www.filmtools...iflosacola.html

I'm not sure, do Kinoflo lamps develop a greenspike over time?


its a very common problem here in india Jonathan ... most of the Kinoflo's r not properly balanced ... As Robert said , aging can b the main problem ..
most of the light's here r old ... being students v cant demand for properly balanced ones ...

Edited by Subhash Sukumaran, 17 August 2007 - 02:54 AM.

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#10 Jonathan Bowerbank

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Posted 17 August 2007 - 11:16 AM

its a very common problem here in india Jonathan ... most of the Kinoflo's r not properly balanced ... As Robert said , aging can b the main problem ..
most of the light's here r old ... being students v cant demand for properly balanced ones ...


Ahhh, too bad :(

In other news...you really need to start writing "we" instead of "v"
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#11 David Auner aac

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Posted 17 August 2007 - 12:01 PM

For a much cheaper way to see if you have a green spike, all you really need is a junk DVD or CD. Use it to diffract the light out into individual wavelengths, just like a prism does. Look at an incandescent, you'll get a smooth spread from red to blue-violet. But look at an ordinary flourescent, and you'll have dark gaps and a green spike. Keep one in your meter kit.


John, that's by far one of the coolest tricks of the trade that were posted here ever since I joined to boards! As simple as elegant! :D

Cheers, Dave
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#12 Tim Terner

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Posted 17 August 2007 - 01:40 PM

I've noticed that whatever John Sprung says in a post/reply , I immmediately take notice of
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#13 John Sprung

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Posted 17 August 2007 - 08:10 PM

John, that's by far one of the coolest tricks of the trade that were posted here ever since I joined to boards! As simple as elegant! :D

Thanks very much.

Note, though, that I've never tried this with kino-flo's. I've used it to determine whether existing lights are incandescent or CFL's, for which it works nicely.

I'd expect that even correctly operating kino-flo's may exhibit a strong narrow green band. It's just that the rest of the light from the phosphors is designed to balance with that green in a way that works on film and video cameras. We'd have to check a good vs. a deliberately overheated kino-flo to know whether it'll detect that problem.



-- J.S.
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#14 Paul Bruening

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Posted 18 August 2007 - 08:34 AM

John,

Become famous with a handy-dandy picture chart of how various light sources should look against a standard surface with the reflected prism effect of your CD trick. Forever on, people in the biz would call it the "Sprung reading". Imagine Vittorio Storaro telling his assistant, "Go get a Sprung off that fixture."
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#15 Richard Andrewski

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Posted 18 August 2007 - 05:25 PM

Something I don't think you mentioned is which type of lamps you're using. The 55w tube for instance, likes a particular orientation but most don't know about it. The socket side should be up. They mention something about this in the Diva operations manual. Regular 4 foot tubes have no such orientation. There can be some color temperature variation if the socket is down. They also mention that even in horizontal mode, "a slight rotation favoring the lamp tips (lamp base higher than the tip will allow for better color temperature stability."

http://www.kinoflo.c.....b Quality.pdf

To answer your question on the HMI, they go through this color change at startup because its just their ignition sequence and they aren't fully stable until about 5 minutes or so.

People talk about color temperature with HMI and fluorescent but its more correct to call it Correlated Color Temperature (CCT) because of the fact that all discharge lighting as previously mentioned in this thread are not continuous spectrum. So any color they exhibit is just a simulation. CRI is still used to measure their color rendering capability but some feel its not adequate and are searching for a better method to encompass all the new lighting technologies--LEDs included.

Edited by Richard Andrewski, 18 August 2007 - 05:27 PM.

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#16 Paul Bruening

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Posted 18 August 2007 - 11:59 PM

Hello Richard,

I have expressed my concern for the color spikes of flos on here before. I dislike flo's unpredictable relationship to costuming and makeup, especially. I prefer full spectrum sources like conventional tungsten and sunlight. I usually get stomped on for not considering flos, kinos particularly, as full spectrum. Most here respond with the argument that kinos are full spectrum light and that whatever the spikes are, they are not manifest on film and video. I have to assume that since these pro-flo posters are so certain, that they must be right and I just don't have sufficient experience with flos to know better. What do you think?
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#17 Richard Andrewski

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Posted 19 August 2007 - 06:26 PM

Hello Richard,

I have expressed my concern for the color spikes of flos on here before. I dislike flo's unpredictable relationship to costuming and makeup, especially. I prefer full spectrum sources like conventional tungsten and sunlight. I usually get stomped on for not considering flos, kinos particularly, as full spectrum. Most here respond with the argument that kinos are full spectrum light and that whatever the spikes are, they are not manifest on film and video. I have to assume that since these pro-flo posters are so certain, that they must be right and I just don't have sufficient experience with flos to know better. What do you think?


Hi Paul,

Fluorescent and ballast-oriented light for video production is my business and what I do but I am honest about what they are and aren't. It's definitely not for everyone and every situation. No, they definitely aren't full spectrum--full spectrum simulation is more accurate. No discharge type bulb (flo, HMI, xenon, etc.) can be. Even LEDs aren't full spectrum. It's just the way they all operate. When you try to take the green out of a flo bulb they simply lose most of their lumen output so not only is it undesirable to remove all green its just not practical. Our eyes respond to green the best so its why the bulbs seem to be so bright.

Also, I'm dubious about claims of 95 to 98 CRI in some bulbs but they also list high lumen output. I went through all this at the beginning when we started making our own bulbs. The higher the CRI, the lower the lumen output. We finally settled on what I call 86 to 90 or >87 CRI ;-). Not because we couldn't make a higher one but because I felt that lumen output is important too. We also upped the power output of our ballasts a bit too in an effort to compensate for the lower lumens of the higher CRI we did obtain. And this is a common trick from film lighting companies that make a flo fixture. That is, for those that use something other than totally off-the-shelf ballasts for their fixtures.

Just take a look at the spectral energy distribution chart on any flo bulb (where the manufacturer is truthful enough to post it!). I posted our bulb test reports along with a test we did on an Osram Dulux L bulb at the same time for interested parties. Our full spectrum bulb looks pretty much like most. You can see what happens is that there are spikes in red, blue and green that are all approximately equal--hence the "full spectrum." You simply don't have those spikes with tungsten.

That being said, tons of people use flo / discharge lighting everyday (in film and video) successfully--including me in my own little productions. Here's the test report:

http://www.coollight...testing-results

The simulation is so good, that its hard to tell the difference many times in the finished video / film product.

As I mentioned, the "standards setters" for the lighting world would love to find another standard besides CRI for measuring color rendering effectiveness. CRI simply doesn't encompass new technology lighting very well. Nor are we going to get people to stop referring to the color out of discharge bulbs as Color Temperature when it should be called CCT. Too much momentum there, so people will go on referring to it as CT when it should be CCT. Too much momentum on the everday use of CRI also.

Just like manufacturers of "HMI" fixtures refer to their units as HMI fresnels or pars which isn't correct. 1). HMI is a trademarked bulb from Osram so they shouldn't be referring to their fixture as an HMI but more correctly should be called a metal halide or HID fixture 2). It's likely they use a Phillips, Eiko, G.E., Ushio or whatever bulb which is just an HMI clone so definitely shouldn't be using Osram's trademark to refer to it. What can you do though? Osram doesn't care, it's just all marketing to them. Just like trying to get people to stop asking for a Coke when they mean any soda will do or a "kino" when it may actually refer to another manufacturer's flo fixture. Do Coke or Kino care--nope...

Edited by Richard Andrewski, 19 August 2007 - 06:31 PM.

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#18 Paul Bruening

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Posted 19 August 2007 - 08:37 PM

Hello Richard,

What an extraordinary answer. Thank you. My issues with flos have actually been with the gaps more than the spikes. I have gotten peculiar results with make up and costuming. Make up is slightly more important especially with lipstick. Some shades of red go purplish and other disagreeable colors that I don't have names for. As well, I have come to notice a "thinness" in color richness when flos are employed. I have detected it with HMI's as well. This has only become an issue since I got my recent degree in graphic design. Before I went to school, my color sense was not sufficiently refined to even notice differing characteristics of light sources other than warm or cool. Since then, Ive gotten troublesomely sensitive to light quality and richness. I blame my painting classes. That's where I had to mix paints and acquired an acute sense of color variations. When you have to mix a new, small batch to exactly match the previous day's painting, you get anal about color.
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#19 Hal Smith

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Posted 19 August 2007 - 09:20 PM

.........My issues with flos have actually been with the gaps more than the spikes. I have gotten peculiar results with make up and costuming. Make up is slightly more important especially with lipstick. Some shades of red go purplish and other disagreeable colors that I don't have names for. As well, I have come to notice a "thinness" in color richness when flos are employed. I have detected it with HMI's as well.......you get anal about color.

Any light with a "liney" spectrum is going to look strange if it's illuminating a surface with a pigment that normally reflects colors other than the emission lines that are in that light. Any color pigment or dichroic has certain wavelengths it reflects, others it transmits, and some to which it basically appears black. I doubt very much if the people who develop pigments and dichroics use anything other than incandescent lighting when testing.
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#20 Jonathan Bowerbank

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Posted 19 August 2007 - 09:50 PM

...Just like trying to get people to stop asking for a Coke when they mean any soda will do...


Is this a global problem? I always thought it was a Northern California thing to say :)

I usually only use Kino's for "daylight" purposes, and like I said, I've yet to experience any noticeable green spike. I assume it could be easily timed out anyway.
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