Jump to content


Photo

Neon Lights: Practical substitutes and pushing

neon led bar colours pushing practicals strip gels

  • Please log in to reply
13 replies to this topic

#1 Anselm Havu

Anselm Havu

    New

  • Basic Members
  • Pip
  • 2 posts
  • Student
  • New York

Posted 24 April 2018 - 10:46 PM

Hi everyone,

 

I'm a long time reader and a first time poster and student.

 

I'll be shooting a shooting a short film in about two months from now which calls for "a bar lit with neon signs". Think of the Bud Light and Heineken signs many bars have as reference. Obviously we won't be able to use any brand signs because of legal issues but I've been thinking of several alternative ways to achieve the same mood. Also real neon signs are expensive and a serious safety hazard.

 

Also keep in mind that the bar will be filled with fog similar to heavy tobacco smoke you see in many movies.

 

The director wants to have neon looking practicals as much as possible. I have two 4 foot quasar LEDs that could potentially be gelled and placed around the background but I feel as if only two tubes wouldn't be enough.

 

1) Has anyone had any experience shooting and sleeving (hard coloured tubes that fit snugly around the bulb) cheap fluorescent units? Do they have a chance of flickering? What about noise? Is there a way of powering them with unaltered wall power or do they require a ballast? If so can they be powered in a way that wouldn't require a housing frame around them?

 

2) Has anyone had experience with cheap neon LED signs? They basically look like neon signs without actually being neon? I'm afraid of cheap LED units because of potential flickering.

https://www.amazon.c...words=neon sign

 

3) This piggybacks off the last one. Has anyone had good experiences with colour shifting LED stripes or ropes?

https://www.amazon.c...n/dp/B01JZ754SG

 

4) I have tungsten lights ranging from 250W to a 2k baby and a set of 2 4' Kinos (tungsten and daylight) at my disposal as well. I'd be using the previous the push the lights. Are there any particular theatrical gels that you have found similar to the hue of neon lights? Green, blue, red, pink etc.

 

Thank you for reading and also thank you in advance for answering!


Edited by Anselm Havu, 24 April 2018 - 10:46 PM.

  • 0

#2 Matt Thomas

Matt Thomas
  • Basic Members
  • PipPip
  • 51 posts
  • Other
  • Fort Wayne, Indiana

Posted 26 April 2018 - 10:20 AM

#3

 

I built my own "sketchy DIY digital sputnik voyager" with an 8ft piece of 1x1 and some color shifting LEDs. Loved it. It was great. Bright enough for what your project is probably going to need. Probably $80 all in. Menards forever!! 

 

...then it stopped working for no reason out of the blue and my heart shattered. 

 

All that being said, DIY led rope lights motivated off of existing practicals could be a great route for you to consider. 

 

Good luck!

 

And if anyone knows how to make my DIY sketch light bar work again you would bring a missing piece back to my soul. 


  • 0

#3 Mark Dunn

Mark Dunn
  • Basic Members
  • PipPipPipPip
  • 2763 posts
  • Other
  • London

Posted 26 April 2018 - 11:08 AM

You didn't use a constant current power supply instead of constant voltage, did you? I'm told it kills LEDs in short order.
Phil will have the last  word on this. He builds lights and seems to know how and why they work..

Edited by Mark Dunn, 26 April 2018 - 11:08 AM.

  • 0

#4 Matt Thomas

Matt Thomas
  • Basic Members
  • PipPip
  • 51 posts
  • Other
  • Fort Wayne, Indiana

Posted 26 April 2018 - 12:22 PM

Sorry to hijack this post. 

 

It was just plugged into a normal wall outlet? 

 

Phil slide into my DM's if you have any thoughts!! 


  • 0

#5 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 12275 posts
  • Other

Posted 27 April 2018 - 04:10 AM

You rang?

 

When I wanted a neon sign for a bit of production design, I used flexible LED strip inside plastic channel, and topped it with some flexible plastic tube covered in PVC electrical tape. It works pretty well, although you can really only do things made of straight lines with it - you can have bends but it wouldn't really work for intricate lettering and so on. It's very cheap, though.

 

If you're hiding things in an otherwise-black background, consider just displaying sign designs on big TVs or computer monitors, or projecting them, but you'll have to ensure you don't see the off-black surrounding area.

 

If you have at least a little bit of money, you can get some of the flexible LED-lit neon tube substitute which really is pretty convincing:

 

AL-FL-NEON-RGB_grande.jpg?v=1474924645

 

That's for signs you want to see. If you just want to cast coloured light on things, consider fluorescent tubes. You can get them in most of the famous "neon" colours, including pink, yellow, blue, red, green and of course a million shades of white. LEDs may not simulate some of those colours that well, so be ready to mix white and coloured LEDs to get the right degree of pastel.

 

As to how to drive them, it depends what you mean by "color shifting LEDs."

 

Flexible LED strip has resistors built-in and can be run from a constant-voltage power supply. It's not a good idea to run them directly from things like camera batteries, as the strip is very much designed for 12V and can be quite severely overdriven when run even from 12V batteries that are freshly-charged, let alone 14.4V lithium camera batteries which can push 18V. Use a DC to DC converter, such as a 12V dimmer, or a 12V mains power supply.

 

LEDs as bare components always require a constant-current power supply.

 

Unfortunately, it's quite difficult to run multi-colour LED strip in a way that will be flicker-free. Effectively all commercial drivers use pulse-width modulation to control the brightness of the red, green and blue (and sometimes amber or white) channels. Sometimes, this is sort of OK at low frame rates, but at high shutter speeds or high frame rates, and sometimes at any frame rate, there can be problems.

 

Nerd stuff: the technical background to this is that the LED strip is almost (not quite) always wired common anode, that is, all the "positive" sides of the LEDs are connected together and the "negative" sides are "pulled down" towards ground to make them light up. The even more technical background to this is that N-channel field-effect transistors are used to build the PWM controllers. N-channel FETs are more effective and cheaper than P-channel FETs, but need their "input" to be at a higher voltage than their "output," so they have to go on the low side of the load they're controlling. P-channel FETs work the other way around, but they're not quite as efficient.

 

Anyway.

 

This means you can't just get several 12V dimmers and gang them all together for RGB colour control, as the dimmers are usually non-isolated, so you can't connect all their positive sides together unless you run them each of a separate battery, which gets bulky and messy and risks issues with touching metal parts of the devices together if they may be connected to the negative side of the supply. Best avoided.

 

I had pondered designing a four- or five-channel linear, that is, non-PWM dimmer specifically for the purpose of running RGB or RGBW LED strip. It's quite feasible, it's just that nobody's ever done it as far as I know.

 

Plan B is just to get red, green, blue, and possibly white strip and stick them side by side. You can get 6mm-wide stuff now, so it doesn't have to be that bulky. Take care, though, that doing this can generate quite a high overall power density. That's great for brightness, but not so great for rule zero.

 

5437174596_e4cd183851_b.jpg


  • 1

#6 Mark Dunn

Mark Dunn
  • Basic Members
  • PipPipPipPip
  • 2763 posts
  • Other
  • London

Posted 27 April 2018 - 04:26 AM

Most helpful.
I've just fitted LED strip in the kitchen - so did I actually need a constant-voltage driver designated for LEDs, or would constant-current have sufficed? They're a bit cheaper.

  • 0

#7 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 12275 posts
  • Other

Posted 27 April 2018 - 04:27 AM

You probably just wanted a 12V power supply, which isn't expensive or difficult.


  • 0

#8 Mark Dunn

Mark Dunn
  • Basic Members
  • PipPipPipPip
  • 2763 posts
  • Other
  • London

Posted 27 April 2018 - 04:32 AM

I read something about the dedicated drivers putting out a high frequency and an ordinary rectified DC shortening the life of the LEDS a lot.

  • 0

#9 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 12275 posts
  • Other

Posted 27 April 2018 - 05:53 AM

The frequency thing makes no sense at all. 

 

If it has resistors on the strip, it just wants DC.

 

Much of that strip is of terribly low quality, though, and tends to start going blotchy fairly quickly. That's likely to mask any other problems, I fear.


  • 1

#10 Matt Thomas

Matt Thomas
  • Basic Members
  • PipPip
  • 51 posts
  • Other
  • Fort Wayne, Indiana

Posted 27 April 2018 - 10:14 AM

Re nerd stuff:

 

https://youtu.be/RXJKdh1KZ0w?t=41s


  • 0

#11 Anselm Havu

Anselm Havu

    New

  • Basic Members
  • Pip
  • 2 posts
  • Student
  • New York

Posted 01 May 2018 - 10:45 PM

#3

 

I built my own "sketchy DIY digital sputnik voyager" with an 8ft piece of 1x1 and some color shifting LEDs. Loved it. It was great. Bright enough for what your project is probably going to need. Probably $80 all in. Menards forever!! 

 

...then it stopped working for no reason out of the blue and my heart shattered. 

 

All that being said, DIY led rope lights motivated off of existing practicals could be a great route for you to consider. 

 

Good luck!

 

And if anyone knows how to make my DIY sketch light bar work again you would bring a missing piece back to my soul. 

Thank you for your answer! I'll be definitely looking into that technique.  


  • 0

#12 Matt Thomas

Matt Thomas
  • Basic Members
  • PipPip
  • 51 posts
  • Other
  • Fort Wayne, Indiana

Posted 02 May 2018 - 04:30 PM

Maybe check out some of these shop lights. Super cheap and super bright. 

 

https://www.amazon.c...0_&dpSrc=detail

 

I found one for $20. Going to replace my old DIY bar with this and find some gels to cut up for correction and whatnot. Maybe not the most controllable but dirt. cheap. and did I mention bright? 


  • 0

#13 Guillaume Cottin

Guillaume Cottin
  • Basic Members
  • PipPip
  • 97 posts
  • Camera Operator
  • Toronto

Posted 08 May 2018 - 01:07 PM

I am surprised that no one mentioned yet the quite popular Astera AX-1 pixel tubes. They're essentially RGB LED tubes. They are rentable and it seems like they can be a great tool for this job.


  • 0

#14 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 12275 posts
  • Other

Posted 08 May 2018 - 07:49 PM

I find having looked around that you can get the flexible neon simulation stuff from China for under $5/metre. Once it gets to that point, there's a limit to how much messing about it's reasonable to do in pursuit of something even cheaper.


  • 0



Also tagged with one or more of these keywords: neon, led, bar, colours, pushing, practicals, strip, gels

Visual Products

Wooden Camera

Paralinx LLC

Gamma Ray Digital Inc

CineLab

Media Blackout - Custom Cables and AKS

Abel Cine

Willys Widgets

Broadcast Solutions Inc

Ritter Battery

FJS International, LLC

The Slider

Rig Wheels Passport

New Pro Video - New and Used Equipment

rebotnix Technologies

CineTape

Aerial Filmworks

Technodolly

Tai Audio

Metropolis Post

Glidecam

Broadcast Solutions Inc

rebotnix Technologies

Willys Widgets

The Slider

Media Blackout - Custom Cables and AKS

FJS International, LLC

Visual Products

Aerial Filmworks

CineTape

Metropolis Post

Ritter Battery

Wooden Camera

Gamma Ray Digital Inc

Rig Wheels Passport

CineLab

Glidecam

Abel Cine

New Pro Video - New and Used Equipment

Tai Audio

Paralinx LLC

Technodolly