Here's the question : when shooting with neon lights in the frame, what problems can I expect. I'd like to ramp from 96 fps down to 24 fps. will there be any flicker problems. are there windows as with HMI. I've heard about electronic ballast's that square up the wave so that the discharge is incredibly fast, eliminating any flicker. any help would be greatly appreciated. thanks.
I shoot in Las Vegas a lot...an awfully lot. The only problem I've had with neon is the brightness. I'll either put it on a neon type dimmer (they do exist) or put some net over the stuff. But mostly I just let it kind of blow-out. As far as flicker, I've never had a problem.
I am not an expert, but I think the answer is you should be safe, at any speed.
I worked on a film that did a day in a neon shop. (Hot as Hell)
The Neon blower (which is a fascinating process) said that Neon runs off of Milli Amps, and THOUSANDS of cycles per second. Yes it certainly does hertz to get a shock from those ballasts.
I could be wrong, but that is what I remember him saying. Good luck
Yup, most neon lamps have RF excitation... there is still a 60 Hz flicker component, but it's not half as bad as with fluorescents. I have shot neon's and occasionally seen visible flicker, but no more than you would see with the naked eye.
However, the induced noise will drive your sound guy up the wall.
Isn't that visible Flicker, caused more by the failure of the Bulb, similar to what happens, when a fluorescent light ages and dies. That funny kind of liquid running of bands.
On that shoot, in the Neon Shop (Marcus Hahn was the D.P. I was an electric)
I remember them shooting with a Plate shot with an Arri IIc, and having to relight the set with tungsten because it wasn't crystal. There didn't seem to be any concern about flicker, from the Neon bulb.
Once again. This is all from Recollection from like three years or so ago.
I've seen very bad (as in reshoot) flicker when shooting high speed (200-300 fps) with neon.
Notes about shooting neon.
It is very bright. If you are shooting neon in daylight, you can still read the tubes. If you are shooting at night, the tubes can overexpose so much that they will be indistinguishable "blobs" of light. I use dimmers to slow the tubes down, but you can only do that to a point before they tube goes out, and that point is typically still to bright. I either put net, or ND filter over them to bring them down more. Sometimes putting brown or black "Streaks and Tips" water soluble hair coloring spray on the tube will be an emergency solution.
If you are using common neon step-up transformers from the neon sign shop, they tube does flicker at twice the AC line frequency, just like regular florescent lamps or HMI lamps running off magnetic ballasts. You have to use the "HMI legal speeds" to stay out of trouble. And I mean *reshoot* trouble. Also in-shot camera frame rate changes are big trouble too. I have heard that there are high frequency power supplies for neon tubes, but I have never seen one.
Another problem to watch out for if you are having neon signs made for a shoot:
If the tubes are mounted on a sign that has a solid background, make sure the neon sign maker paints the back side of the tube, that faces the background of the sign, opaque black. This is necessary because the neon, that close to the sign backing that it is mounted on will overlight that area, even if the tubes are dimmed, rendering a blob of light rather than a defined tube shape. I got burnt by this when we were in a rush for a sign, the neon maker wanted to paint the back of the tubes as usual, and my buddy the Art Director said "Naw, don't bother with that, we don't need it" .....One reshoot day later, I discovered how wrong he was.