DIY Kino problem

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paddingtonrutherfordbrown

Member
Hallo everyone,

I made myself a Kino Flo using 4x 55w Compact Flourescents and reflectors and ballast from ahsupply.com, but the output is not constant.

There is a slight shift in colour temperature and brightness that seems to alternate every three seconds or so.

The change is not particularly noticable and you can only really see it in a jump cut (or fast-forwarding through footage), but does anyone have any idea what could be causing it?

The ballast I am using is 230V AC, 50,000/60,000Hz, max current 0.57A, which seems to fit the bill (I'm in the UK, by the way), but I also noticed that A&H (based in the US) are now selling a slightly different ballast for international buyers, which they didn't when I bought from them.

Thanks in advance for any help.
Jack
 
its probably a weakness in your ballast. kino flos cost what they do for a reason.
its not easy getting good, effective light from off the shelf fluorescent components... or we'd all be doing it.
 
There is nothing magic about name-brand fluorescent fixtures. There is a bit of technique in making high-frequency ballasts work properly. Is your reflector metallic? Is it grounded to the ballast and power cord? Are there any special instructions associated with the ballast you are using?
 
There is nothing magic about name-brand fluorescent fixtures.
Click to expand...
there is if that "brand" has invested time and money to overcome inherent problems with the hardware...

ive never seen anybody show up with home-made fluorescent lights. even BAD home-made fluorescent lights. about the cheapest, effective fluorescents ive seen is the "cool lights". they are about 30% cheaper than kinos.
 
wgzn said:
there is if that "brand" has invested time and money to overcome inherent problems with the hardware...

ive never seen anybody show up with home-made fluorescent lights. even BAD home-made fluorescent lights. about the cheapest, effective fluorescents ive seen is the "cool lights". they are about 30% cheaper than kinos.
Click to expand...

I always carry 4 Home Depot twin tube, 48" T-12 fluorescent shop lights, that cost, I think around $8.00 a piece. I have some Optima 32 3200K tubes, some Optima 50 5000k tubes and various consumer brand tubes for them. I would never say that these lights are better than Kino-flos, but they are some very, very handy lights. I have modified the mounts, and reflectors, but I have not touched the ballasts or other electrics. They work fine, and are very effective lights for portraiture.
 
Richard Crowley said:
There is nothing magic about name-brand fluorescent fixtures. There is a bit of technique in making high-frequency ballasts work properly. Is your reflector metallic? Is it grounded to the ballast and power cord? Are there any special instructions associated with the ballast you are using?
Click to expand...
Hi Richard,

The reflector is metallic, and it's not grounded to anything. There were (as far as I know) no special instructions for the ballast.

Thanks for your help (and everyone else too)
 
wgzn said:
ive never seen anybody show up with home-made fluorescent lights. even BAD home-made fluorescent lights. about the cheapest, effective fluorescents ive seen is the "cool lights". they are about 30% cheaper than kinos.
Click to expand...
Well, that's definitive, isn't it? Curious why you hang around in an DIY forum?
 
David,

I saw those yesterday at home depot. I liked them because it came with a plug. Some of the others were to be wired to a switch.

One of the employees told me that they couldn't be mounted flush because it needed a way for heat to escape.

Do you mind posting some pics on how you mount them to stands?

Thanks!

David G. Smith said:
I always carry 4 Home Depot twin tube, 48" T-12 fluorescent shop lights, that cost, I think around $8.00 a piece. I have some Optima 32 3200K tubes, some Optima 50 5000k tubes and various consumer brand tubes for them. I would never say that these lights are better than Kino-flos, but they are some very, very handy lights. I have modified the mounts, and reflectors, but I have not touched the ballasts or other electrics. They work fine, and are very effective lights for portraiture.
Click to expand...
 
Since paddingtonrutherfordbrown never returned (after 1.5 years), we will never know the rest of HIS story.
Another possibility was that the switching frequency of the ballast was some very close multiple of the frame/shutter speed.
If the color shift was visible to the naked eye, then some instability in the circuit/ballast/tube would be suspect.
But if the color shift was only visible in the recorded video, then I would be more likely to point at the switching frequency as the problem.
 
Hi Richard,

Apologies that I didn't continue with this thread..I planned on doing some tests, earthing the reflectors, and getting back to you with the results, but I just never managed to find the time.

I'm on the DIY forum because I made a couple of lights from scratch and they've got a problem that I don't know the cause of..

But so I plan on doing these tests in the coming weeks and I'll provide info on what I find-I used the lights again a few months ago and noticed that on faster shutter speeds (I was using a DLSR, and taking both stills and video (though in the past I've used them with an HVX with the same colour shift problem)) there are darkened stripes that scroll up the LCD (though they don't seem to be present on the stills). My guess would be that the ballast's frequency isn't high enough, though, as you seem to have noticed, I'm an ignoramus when it comes to this stuff.

One other thing, though-do you think it could possibly be because I'm using US ballast in the UK?

Anyway; I'll try out a few things and get back to you.

Thanks again for your help with this.
 
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