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Fluorescent Practicals


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#1 Duncan Trevithick

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Posted 19 January 2013 - 11:57 AM

I'm looking to buy some cheap fluorescent tubes which I can easily fix to the set as practicals, similar to Mr Deakins & Mr McDowells' use of them in In Time:

Ideally I want them have small fixings on the end for the power cables with a separate ballast, like Kino Flo bulbs, so I can just tape them to the set and hide the cables. I've looked at these but they seem to need a rigid fixing at one end to power them, and I can't see any information about the ballast.

I'd like them to be daylight balanced and not too green.

Can anyone recommend a solution?
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#2 Phil Rhodes

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Posted 19 January 2013 - 12:54 PM

You can piece together a fairly reasonable solution from off-the-shelf lighting parts. It is done fairly regularly by enterprising gaffers.

High frequency electronic ballasts are reasonably cheap; you can get dimmable ones (certain types require nothing more than a variable resistor to control dimming) although they are rather expensive. Buy the best ones you can from a known company; these are likely to have the fewest problems with flicker. Ballasts are specific to the tube wattage. Twin tube ballasts are generally OK with just one tube attached, but check. Particularly stupid ballasts (which you won't have bought, since you'll have your eye on quality) may repeatedly try to start absent tubes and generate high voltages which may create ozone, arc over and damage things or start fires, or damage themeselves, but that's reasonably rare.

Connections to the ballasts are usually via a rather inconvenient push-in terminal block which is really designed to work with the solid-core copper wire that's usually used to wire up fluorescent ceiling panels. With care and a tidy hand, they will grip stranded core wire too, allowing you to wire things up using more flexible cable. You will undoubtedly want to put the ballasts in a box with a switch, appropriately-rated fuse and a mains connector, although it's probably best to keep the tubes (or at least the tube end caps) permanently wired to the ballasts. Use appropriate strain relief to prevent mains input and tube output wiring being pulled out of those rather inadequate push-in terminals. It may be difficult even to discover what sort of connector rating is actually required to accomodate whatever the ballast puts out (it's invariably more than mains), so just wire it direct to the end caps.

Colour quality is determined by the tubes you buy. Decent ones are, again, not cheapest, but photographic tubes with a CRI in the 90s (which are invariably daylight balanced as opposed to tungsten) are available for not-impossible amounts of money. I strongly recommend plastic shatter sleeves as used in the food service industry, not because they will prevent things from breaking (though they help), but because it is a lot easier to clean up afterward. A film set is a horribly chaotic environment to be handling unprotected four foot long, one inch wide glass pipes full of toxic chemicals.

Connecting to the ends of the tubes can be a bit of a bind. Almost all of the commercially-available tube end caps are somewhat reliant on being fixed into a fairly solid rectangular frame to apply pressure and keep the caps on the ends of the tubes. The only people I'm aware of who make the type which hang on reasonably tight are Kino-Flo. They do sell them as spare parts, but depending your appetite for the heath-robinson solution, there are other approaches. I've done it with screw terminal blocks, which you can attach to the tube pins pretty securely, but you aren't going to win any electrical safety awards and this should really only be done inside an insulated or grounded touch-proof housing.

Anyway, that's my info-dump on how I did it.

P
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#3 Freya Black

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Posted 19 January 2013 - 01:37 PM

Connecting to the ends of the tubes can be a bit of a bind. Almost all of the commercially-available tube end caps are somewhat reliant on being fixed into a fairly solid rectangular frame to apply pressure and keep the caps on the ends of the tubes. The only people I'm aware of who make the type which hang on reasonably tight are Kino-Flo. They do sell them as spare parts, but depending your appetite for the heath-robinson solution, there are other approaches. I've done it with screw terminal blocks, which you can attach to the tube pins pretty securely, but you aren't going to win any electrical safety awards and this should really only be done inside an insulated or grounded touch-proof housing.


I have tubes exactly like the ones in the picture. They are about 6ft long and I fished them out of a skip as a high street clothing shop was destroying its window display. I was dead popular with the bus driver on the way home. Are they T12? I don't remember. Anyway mine have high frequency ballasts and come in a plastic tube container with a hook at one end so you can hang them vertically with the mains cord coming out the bottom. They are preety special and I wish I could remember who makes them, but sadly I can't.

Anyway, this stuff is out there in the world of commercial lighting design.

Freya
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#4 Duncan Trevithick

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Posted 24 January 2013 - 06:38 AM

Thank you, that's all very helpful. I'll have a look into those solutions.
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