Hi:

I had a question. Can a cheap Chinese versus an OSRAM, versus a KINO ballast for Diva or faux Diva fixtures affect the actual color temp of a lamp?

For example, if I get a cheap chinese 2/4/6-bank fixture, but I lamp it with Kino True Match lamps, will it give me some other color temp than what it is supposed to do?

In other words, is the lamp the sole determinant of output color temp, or is the ballast the sole determinant, or is it some combination.

Thanks

One thing which will affect your colour balance is the temperature. The contruction of the eastern copies leaves much to be desired when it comes to cooling and the reflectors tend to push a lot of heat back into the tubes. When the tubes get hot their green spike increases dramatically, even Kinoflos will have a tendency towards green (and they're normally slightly on the magenta side of neutral).

Likewise if the ballasts, in an effort to be "flicker free" don't allow the gases to "rest" for long enough, the tubes will increase in temperature. There doesn't seem to be any difference in performance (colour temperature-wise) between Kino and Osram flicker-free ballasts though. Mind-you that was just using a Minolta colormeter to check the balance, maybe hyper-sensititve lab equipment would show a slight difference.

This is from personal experience when I was buggering about testing various LEDs and Fluorescents for seminars. The idea was to be able to say with conviction... "you don't need to buy Kinos and Gekkos, you can get the same result with Chinese gear" but it became obvious that the opposite was the case.

Hi Guys,

A ballast is only in the circuit long enough to fire the tube. Once the gases have ignited, the ballest drops out of the circuit. Reflectors will have a bearing on heat but this is mainly "hot heat" or traditional temperature, colour temp is measured in degrees Kelvin, not strictly as "hot heat". Therefore, provided the ballast fires the lamp and ignites it, the rest is dependent on the lamp itself. i.e. if it's tuned to burn at 5000 degrees K, that's what it'll burn at. Hope this helps.

Here's a bit of info for you.

Kelvin Color Temperatures (http://www.3drender.com/glossary/colortemp.htm)

Al

Once the gases have ignited, the ballest drops out of the circuit.

Not correct. The ballast controls the current and waveform going to the tube(s) throughout it's entire cycle.

The old inductive ballasts could, and did, do some weird and wonderfull things to the sinusoidal waveform between the in and out ports.

The new electronic ballasts can do even more ( read worse) if they're so inclined.

Dependent on design and manufacture, they can turn a sinus waveform into a sawtooth or just about any other shape they so please, thus significantly affecting how long a tube is in the ramp up and ramp down phase of operation.

I have a batch of fixtures here with "warm white" tubes and electronic ballasts, they're actually pink, and no, they're not faulty, just crap.

I have another set of the same fixtures, same manufacturer but different make of ballast, the "warm whites" are now blue!

So, as the original question was: can a ballast be responsible for a colour shift in a tube, the answer is, my word, yes.


CS

...I stand corrected........

bow... bow...scrape.... scrape.....

Al

PS.Could be those Kiwi ones are a bit queer.............. ;)

They're actually.................drum roll.......................Chinese!

Queer, definately. Chinese most certainly. Crap, idubitably.

Ho Hum.


CS

I feel as if the Australian, Kiwi and English contingent here must all be electricians on the side. Thanks gents for enlightening me about the inner working of ballasts. When I built my own Kino knockoffs, I sourced a high speed, high quality fairly expensive ballast and I have been quite happy with the results with the Kino tubes but it is very interesting to hear about how the ballasts actually function. Thanks.

Dan

Thanks for the answers. It does seem like there are some conflicting opinions. At the least, it seems that color temp can be affected by ballasts (or should I type colour for the Commonwealth types).

Robin, so if I set up a color meter (Minolta II) on a stand and point my fluoro fixtures at it and get a reading after the light settles. And then I turn a fan on to blow across the tubes, cooling them, I will see a change in color temp? Interesting. I'll try that.

Dan:

I have some Chinese fixtures. I am thinking of replacing the existing ballasts with some good ones. Can you recommend some model numbers and approximate prices? Are they dimmable ballasts? Can you share any links to your project?

Thanks to all

If your lamp has efficient cooling, then there shouldn't be any difference since the design of the unit and reflectors is doing its job. But if you can work out a way to increase the heat of the tubes without damaging your unit, you will see a shift towards green.
The Kelvins will hardly change at all, just the green content.

In the case of your oriental units, it's probably cheaper just to bung a bit of minus green gel (a quarter or even an eighth) in front of it rather than start replacing ballasts.

Hi:

I had a question. Can a cheap Chinese versus an OSRAM, versus a KINO ballast for Diva or faux Diva fixtures affect the actual color temp of a lamp?

For example, if I get a cheap chinese 2/4/6-bank fixture, but I lamp it with Kino True Match lamps, will it give me some other color temp than what it is supposed to do?

In other words, is the lamp the sole determinant of output color temp, or is the ballast the sole determinant, or is it some combination.

Thanks

In general the mixture of phosphors in the tube is the main factor. Very badly designed or faulty ballasts can create a pinkish glow at one end of the tube and shorten lamp life. Pretty decent explaination of all things fluro here: Fluorescent lamp - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Fluorescent_lamp)

In the case of your oriental units, it's probably cheaper just to bung a bit of minus green gel (a quarter or even an eighth) in front of it rather than start replacing ballasts.

yeah, but I love to hack things. Mostly, I want dimming capability. The current ballasts do not have that. So, Dan, do you have a link to your projects or can share the model #'s that you used? Thanks, Mike

The ballast that you're after is an Osram QTI 2X28/54/220-240 DIM UNV1.
OSRAM|Professionals|ECG|ECGs for FL and CFL|Dimmable ECGs with 1...10 V interface|QTi...DIM-T5|index (http://www.osram.com/osram_com/Professionals/ECG/ECGs_for_FL_and_CFL/Dimmable_ECGs_with_1...10_V_interface/QTi...DIM-T5/index.html)

That one will run 2x 55W tubes. Dimming control is by 0 to 10V analog input. Pretty certain Osram have a dimmer module designed to mount in a wall plate that can be cut down very easily to fit into a fixture. One module will control at least 3 ballasts but darned if I can find the module on Osram's site.
For my own instruments I made up a very small zener diode regulated 10V supply with a pot, realistically you cannot dim these tubes below around 10% or wierd things happen so my dimmer control does around 1 to 10V output.

Thanks Bob, but that seems to be the 220-240 volt model. I am in the US. I'll see if I can locate an equivalent model. But if prices for the US model are the same: 80 euros each, then wow! That may be a cost prohibitive change.

OK, here is the Sylvania brochure which shows the US voltage models:

http://ecom.mysylvania.com/miniapps/FileNet2/FamilyBrochures/FAM_BROCH1.pdf

pages 42-43 show the Helios line of dimmers. Pages 28-29 show wiring diagrams and a list of control manufacturers

OK: so I found this in a Kino Flo brochure. You were right.

The physical heat of the lamp directly influences color temperature and lumen performance and lamp life.
In order to maintain a stable color performance the lamp requires:
a cool spot at the tip of the lamp
a horizontal orientation
or a vertical orientation where the base of the lamp is above the lamp tip.

OK so I can now share something with you. I had purchased several 6-bank oriental fixtures. I, being prone to experimenting and looking for cheaper alternatives, purchased some 5500K lamps from alzodigital.com. They were dirt cheap and came with free shipping on orders over $100. So far so good.

I put them in the fixtures and took out my handy Minolta Color Meter II. I got an average temp of 8,000. Yes, I said 8,000. I measured individual lamps and got temps that ranged from 7500 to 8800. Also also found them to be very very green. a -11 on the meter, which is close to a full minus green.

Now I had originally started this thread to see if somehow it was the ballasts that were causing this huge gap. The conclusion sounded like the ballasts may have an affect, as would thermal temperature, but that its mainly the tube.

So on that note, I bought a slew of Kino Flos. They came today and, hit the fricking correct temp at start up. magenta/green reading was a -5. Not bad. I expect that after burning in for 100 hours, I will get some more stabilized and less green results.

Just goes to show you: save $$$ on cheap fixtures but don't scrimp on lamps.

Cheers

OK: so I found this in a Kino Flo brochure. You were right.

The physical heat of the lamp directly influences color temperature and lumen performance and lamp life.
In order to maintain a stable color performance the lamp requires:
a cool spot at the tip of the lamp
a horizontal orientation
or a vertical orientation where the base of the lamp is above the lamp tip.

The industry standard (used by Lowell, Arri etc) Osram Studioline tube is spec'ed to burn in any position:OSRAM Studioline 55W (http://catalog.myosram.com/zb2b/b2b/start.do?browsername=mozilla%2F4.0%2520%2528compatible%253B%2520msie%25208.0%253B%2520windows%2520nt %25206.1%253B%2520wow64%253B%2520trident%2F4.0%253B%2520slcc2%253B%2520.net%2520clr%25202.0.50727%25 3B%2520.net%2520clr%25203.5.30729%253B%2520.net%2520clr%25203.0.30729%253B%2520media%2520center%2520 pc%25206.0%253B%2520officeliveconnector.1.3%253B%2520officelivepatch.0.0%253B%2520.net4.0c%253B%2520 .net4.0e%2529&browsermajor=4&browserminor=4)

I'm a bit nervous about KinFlo fluro lamps. We've got a Kino 800 and the tubes in that run very hot. A 6 foot tube handling 100W is pushing it. Those tubes have the option of a plastic safety sheath and not only does that affect the cooling, over time it bubbles up at the ends of the tubes.

A fluro tube should have a usable life of around 8,000 hours. I've run the Osram 55W tubes in an outdoor sign for over 20,000 hours at around which point there's just no mercury left in them. Needless to say before that the CT was getting a bit off but it is just a sign :)

A fluro tube should have a usable life of around 8,000 hours.

Yes, but is this a useful life for cinema lighting? I've read that both color temperature and CRI change as the tubes age. Many cinema lighting people seem to change out bulbs every year or so just to maintain a constant light quality.

Has anyone done any testing for this? IOW, is this a real problem or just a myth? The only way to tell would be to do the experiments (I don't have the space or the equipment) and chart the changes over time. I'm sure it's been done and probably published. But I've not seen such results yet. Anyone?

Bruce: The Kino document which I previously cited states that the useful life for film work is more realistic than the full 8K hours. Kino says its around 2500 hours.

BTW, thanks to all for sharing your thoughts and making this a lively discussion.

Just about every broadcast studio I work in has Kinoflo tubes, even if they have other units. There doesn't seem to be a "standard" period after which they're changed. I just go in, fire 'em up and then point out the tubes (if any) which are a different colour to their neighbours and get them changed.

So I would guesstimate that they last a maximum of 5000 hours before they start to change colour. Kino are probably covering their bums when they quote 2500 hours. They may well go on for another 15000 hours but by that stage you would have a mulicoloured grid up there.

There is no doubt that Kinos are the most accurate, followed by Osram Studiolines. Place the two in the same unit and you can see the difference, with the Osrams looking slightly green in comparison. For the sake of a few dollars, it's worth getting the Kinos since they will mix with tungsten lamps (I mean, of course, the 2900 or 3200 tubes) or true daylight without any filtration.

Just about every broadcast studio I work in has Kinoflo tubes, even if they have other units. There doesn't seem to be a "standard" period after which they're changed. I just go in, fire 'em up and then point out the tubes (if any) which are a different colour to their neighbours and get them changed.

So I would guesstimate that they last a maximum of 5000 hours before they start to change colour. Kino are probably covering their bums when they quote 2500 hours. They may well go on for another 15000 hours but by that stage you would have a mulicoloured grid up there.

There is no doubt that Kinos are the most accurate, followed by Osram Studiolines. Place the two in the same unit and you can see the difference, with the Osrams looking slightly green in comparison. For the sake of a few dollars, it's worth getting the Kinos since they will mix with tungsten lamps (I mean, of course, the 2900 or 3200 tubes) or true daylight without any filtration.

The Osram tubes can be had in both daylight and tungsten. Both Osram and Kino tubes have a green spike, Kino's own spectrographs clearly show this. I cannot find the graphs for the Osram tubes online at the moment.
Color shift over time is a common problem for all discharge lamps, HMIs shift around 1 deg per hour.
The Osram Studioline tubes are not Osram's highest CRI tubes, they do a better range of lamps for museums and art galleries but they don't come in a 55W version. Generally the Studioline tubes are considered more than adequate for video but not good enough for film.

If it was simply a matter of using Kino tubes in the same instruments to feel better about your lighting I'd say go for it. The issue I see is only Kino's instruments are designed to meet their requirements for lamp orientation. The Lowell and Arri instruments that are pretty common in studios down here and the Lupo instruments out of Europe that we use plus all the Chineses cheapies all have the lamp base down, base up and down or base level with tip. That is fine with the Osram tubes however Kino are very specific about not running their lamps in any of those orientations. That might just be FUD however the Kino lamps do appear to have subtle differences in their design compared to the Osram tubes.

So I'm starting to get serious about fluorescents and like many out there can't afford to buy 6 kino flo fixtures. Looking at them, there seems to be a lot of added electronics and dimming which I just don't need.

My end purpose is to permanently light a green screen that will be 12' wide, 9' tall, and have a 9' floor, all paint with the cyc transition from wall to floor.

I recently was told about Kino's 4' T12 75 watt green screen bulbs and they sound like the ticket. Curious about mounting in a cheaper shop-light style fixture re-ballasted properly. I will be making my own mounting brackets and barn doors too. And painting the fixtures matte black and putting in a silver reflector too. I have found electronic ballasts at the proper rating for about $40, fixtures for about $30 and the bulbs are about $120 for a six-pack. Seems like a deal if it works! Just curious if anyone has had luck trying this. Especially curious about the green screen bulbs!

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