Where to get high frequency flourescent ballast? (DIY Home made Kino Flo question)
 

I've been reading up on home made kino flo's and have found the following resources:

http://www.dvinfo.net/conf/showthread.php?t=50192o
http://www.dvinfo.net/conf/showthread.php?t=9751
http://www.dvinfo.net/conf/showthread.php?t=45182
http://www.dvinfo.net/conf/showthread.php?t=12671
http://www.studio1productions.com/Ar.../FL-Lights.htm

One thing I have yet to find though is where to purchase 25kHz or higher output electronic ballasts. I went to my local electronic supply store and they called their supplier, Sylvania, who said they have nothing of the sort. I know the ballasts must exist as

A) people mention having them on this forum in the above threads
b) when I do a google search for them I find chinese manufactuers listing them for sale.

Does anyone know a retailer which carrys affordable (under $100) high frequency ballasts?

yes, but I'll do you one better. Little secret called ahsupply.com
They sell kits WITH AMAZING REFLECTORS for 2 bulb setups, about 65 with everything but an enclosure and bulb. All wiring, caps, etc included, and I think they run at 60 khz. ot 60hz, 60 KHZ. I use them for video, stills, you name it. With their reflectors they are simply amazing! About 2x the output of a kino diva 2 bank. But, if you really want a completely DIY solution, the ballast they use is a Fulham Workhorse 5. Good for about 120 watts in any bulb configuration. Google "Fulham workhorse" and you'll find that most commercial lighting suppliers will sell you their ballasts for about $30 or something (to drive 2x55w bulbs). I thought long and hard, and ended up with AH supply, because their reflectors are better than anything I've ever seen before (arri, kino included) and would cost WAY too much to buy separately or make. They are very very very very efficient. Comparable in output more to kino's parabeam series. Work to the wise - use good bulbs! Osram studio's or Kino's. You'll kick yourself later trying to get away with $9 bulbs when for $23 you can have the right bulbs and not need filtration or frustration. To your eye, they may even look the wrong color, but on film, they record perfectly. Hope that helps!

Model number for the ballast you mentioned is WH5-120-L - The spec page is here:
http://www.fulham.com/Detail_Ballasts.php?ID=WH5-120-L
EDIT: It looks like all electronic ballasts have high enough output frequencys

An article I found says all electronic ballast runs at more than 20khz - can anyone with more of an electrical engineering background verify this?

Yes,
electronic ballasts run at around 20KHz. The supply of course is 50/60Hz going into them.
The average electrical supplier would not understand this, just tell them you want an electronic ballast.

BTW Osram make a full range of ballasts to suit their Studioline tubes. They're also available with dimming control via 0-10V input.

According to the studioline webpage (http://www.sylvania.com/BusinessProd.../DisplayOptic/ ) it looks like they use standard Sylvania QUICKTRONIC electronic ballasts.

OSRAM STUDIOLINE®
Compact specialty fluorescent lamps with special phosphor coatings designed for TV studio, cinematography, and photographic applications. STUDIOLINE lamps are suitable for 120V or 277V applications and can be dimmed to one percent of light output with QUICKTRONIC ballasts

yeah, the wall power is 60hz (usa) but the output (operating) frequency of the workhorse is 60 KHZ. It is twice the recycle of the standard electronic ballas - I talked to them on the phone a while back.

One thing to note - Kino's over-drive their tubes, so SOMETIMES (and I'm not positive which fixtures) they compensate in the phosphors of the tube to make up for the fact that they overdrive (i.e. adding more magenta). Not positive which tubes though. I have Osram daylight tubes and they register 5500k with no green spike.

oh one other thing - I've found that dimming the bi-tube lamps makes them color shift VERY badly. Kino's, Moles, Arris, they all do it when dimmed. It's a feature of the lamps. ND is a much more predictable way to dim (or back them off) bitube fixtures. Straight tubes don't do this, so if you're making a fixture for t12 type lamps, should not be a problem using dimming ballasts. Be forewarned though.

Also, ballasts meant for t8 tubes will overdrive t12 tubes. Even if it is electronic, it must be auto-adjusting in order to drive it correctly on a different sized-tube. Not all electronic ballasts are auto-adjusting. The workhorse ballasts are auto-adjusting. I know it's bizarre logic, but wider tubes take less power to drive. They have less light output but they also take less voltage. That said, it is possible that Kino uses electronic t8 ballasts to drive their t12 tubes, achieving their "overdrive." Just a theory.

Must say I've never noticed a color shift dimming single D tubes run off electronic ballasts, not once the tubes are warmed up. That can take a few minutes at full power and a lot longer if they're dimmed.

I agree about Kino overdriving their tubes, they seem to run pretty hot and not last anywhere near as long as regular tubes.

Yeah Bob, they do take a LONG while to warm up, but even after that, all 2g11 lamps shift pretty badly when dimmed. I asked a few othe people about it too, and it has to do a lot with the diameter of the tube. Film-safe lamps don't eliminate the green spike, they correct for it. In the phosphors of the tube they add magenta so you don't have to gel magenta later. Problem is, when you dim a tub of this size, the temperature of the mercury arc drops significantly and outputs a lot less green - hence a color shift. When it's fully warmed and fully powered, the phosphors are matched to the exact spectrum of the arc. On wider tubes, there is less of a temperature difference between fully on and dimmed, so much (if at all) less noticeable shift.

All that said, if the tubes are brand new, it will matter a lot less than tubes with a few thousand hours.

Are there over-the-counter compact fluorescents which are suitable for video? While I was at the electronics store I asked if they used electronic ballasts and told they do, which means there shouldn't be an issue with flickering. They also appeared to have CFLs in the suitable Lumen range, although none had their CRI listed on the package.

Then again I haven't even checked the price of the CFL they sell at photo stores, so maybe it isn't even worth it for the minimal cost savings

Yes and No. It all depends on how much gellin' you want to do. Video has a much easier time balancing the spikes of fluorescent lamps than film does. Kino's were invented for film. You can certainly get creative and use over the counter lamps and gel your other lights +CTG (not sure what percentage, all depends on the lamps you choose) to match, and take a white balance reading. The camera will effectively balance out the green spike. To be completely honest though, these lamps have VERY long lifespans compared to tungsten, and even the kino's are comparable in price to tungsten globes. For an arri, you'll spend about $20 for a lamp in a 650 fresnel. For a kino lamp you'll spend about the same. The difference is that corrected fluorescents last 10's of thousands of hours (if treated well). My personal choice was to spend the extra cash and save the headaches later with gelling all other lights (or the flo's and losing power). Plus I use them mixed with my strobes for still photography, and I know they match when I use Osram daylights.

Jaron - Great Tip!
 

Hi Jaron:

I have been working on a homemade Kino fixture, which I will show all of you guys in a few weeks when I can get a spare few hours to finish it. However, your link to AH Supply blew my mind, their kits seem like such a deal and I like the idea of the MIRO reflector. What are you doing for eggcrate and diffusion for your AH lights?

I am ordering the 2x55 kit tomorrow, seems like it fits the bill. At $64.99 ea. plus about another $42.00 for each set of Kino 5500 tubes, seems like I have a Diva 200 for about 1/8th of the cost. High frequency ballast, same output with the good CRI, etc.

Brilliant find, thanks for the tip!

Dan

Jason - what do you use for enclosures / mounting mechanisms?

Well, I don't live far from Chinatown / the restaurant district. I found a place that does custom stainless mfg cheap and well, so I have this guy build me pans and yokes. I bring them home and drill / pop-rivet the pieces together. REALLY durable. Actually they are fairly light weight too, believe it or not. I'm trying to figure out a new way, so I'll keep you posted. In the meantime, this works well, and they can really take a beating (unlike kinos).