Flickering Lights

[mad_hatter]

Slightly embarrassing, since I work for a lighting company, so I should be able to figure this out, but...

Anybody know of any clever ways to make a regular light bulb flicker? Having searched Google, the concensus seems to be that the best way is to wire a starter into the LIVE. So that's what I've tried:

https://www.youtube.com/watch?v=x0hlxUjd1AA


Unfortunately, this isn't quite what I was going for. I would like the light to stay on permanently, then flicker off randomly, more intermittently than that in the video.

Any ideas?

 

[knightly]

If you were to use that spinning disk, and cut lines of varying width into it, you could program your flicker with the flicker box… adding a second interference disk could create your randomness if you set it to a slightly different speed than the first.

 

[mad_hatter]

Thanks for that Knightly! That's actually really great thinking! I'd be much more comfortable with that than the "accident-waiting-to-happen" conductive disc version.

This is my project for tomorrow afternoon, so hopefully I'll be able to try this!

 

[jax_rox]

I've done this before with household tungsten/halogen globes (CFLs look sh*t on screen ) either in prac lamps, or a china ball using one of these from IKEA that cost ~$15:

Depends if you need the globe to be a t maximum brightness or not. If you want dimming level as well as on and off flashing, then a simple dimmer will work. If you need it at max brightness and what that flash on and off, rather than a level dimming, you'll want to look into a proper dimmer box. They generally have 'flash' buttons:

You can generally rent these quite cheaply from a stage lighting shop.

There's also 'digital' dimmers, that enable you to do both (dim and flash) quite easily, all automated, and without the necessity for a flash button:

Then there's also lights that have such controls built into themselves, for example the Creamsource:

Lastly, there's the trusty flicker box, which is a little less versatile than a dimmer, but easier to make it flash, than having to have someone sit there and hit the flash button.

 

[mad_hatter]

So, I had a little play today, and built myself a flash box. Unfortunately, it requires manual operation, but it's pretty close to the effect I was after. Here's the results:

https://www.youtube.com/watch?v=9EIUknuSuEI


And, to ruin the illusion, here's what it looks like without the china ball:

https://www.youtube.com/watch?v=FJp_lwwfXuU


As you can see, it still requires a button to be pushed, but it's much less crude, and much more efficient, than somebody flicking a light switch. The green button switches the light off for as long as it is pressed. The red button changes the circuit to the flicker bulb. Half a press of the red button also switches the whole circuit off, so is probably the only button that's actually needed.

Unfortunately, the flicker bulb is only 3 watts, so is much dimmer than the other bulb.

Hopefully, in the coming days I can set up a couple of shots using the flickering light for it's intended purpose. Fingers crossed it'll look okay.

 

[knightly]

Is the lamp meant to be in shot as a practical or used as a source? If in shot, you may need to dim the main light as it'll be a little bit too bright to offset the main lighting you'll be using to actually light the shot. That 3W light might be perfect for that fixture. You can get socket based dimmers for $10 that can attenuate that main bulb's brightness for you at walmart and the like.

 

[mad_hatter]

I guess it'll be both. It's main use will be as a practical, but I had hoped to light a wall with it as well, and have the flicker visible on that wall. The whole thing will actually be set inside an aluminium reflector.

The main lamp there is 25w. What I may do is set this up twice; once with a lower power lamp for shots with the light in, then again with perhaps a couple more flicker bulbs for whwn it being used as a source.

I guess I need to just experiment...

 

[Will Vincent]

You only need like 3 more parts to be able to change what you currently have to allow the low wattage flicker bulb to make the higher wattage bulb flicker properly. I don't think this is going to work out great as either a practical or source light honestly.. there's a pretty bit disparity between bulb wattages. It might cut it as a practical, but 3w isn't going likely to be enough power to work as a source light.

 

[mad_hatter]

Will - As the light flickers, the scene would essentially be dark. There would, of course, be other lights illuminating the scene, so everything would still be visible. But the 25w (as it is now) would essentially be a key light. I would like the flicker to be visible, but the light would, for all intents and purposes, be off.

I envision only a couple of shots, where the light would be practical, in which case, I would be stepping the wattage of the key down, only to ensure that it doesn't blow out. In this instance, there would be another light source providing the key.

At least that's what I'm thinking....

And, if by a few more parts, you are meaning a photocell, I did try this. Unfortunately, the flicker didn't transfer; the cell registered the flicker bulb as being always on. Perhaps a more sensitive photocell may solve this....?

 

[knightly]

just for reference... at 24fps, 1/48 shutter, ISO100... I need to expose with about 500w key @ 6-10 feet to get a decent exposure with any possibility of control over my aperture. Lowering the light will introduce grain as you are forced to raise the ISO, and make focusing difficult as you open the aperture to let in more light.

Cameras are hungry... video more so, as you can't reduce the shutter speed without introducing weird motion artifacting. Feed them with light... they'll poop out beautiful images for you.

 

[Will Vincent]

if by a few more parts, you are meaning a photocell, I did try this. Unfortunately, the flicker didn't transfer; the cell registered the flicker bulb as being always on. Perhaps a more sensitive photocell may solve this....?

In the instructions in that flicker box plans link I posted, the author was fairly clear that some fiddling with light/sensor positioning was likely. Perhaps you need to play with the distance from the flicker bulb, as well as where on the bulb it's positioned in relation to the bulb's filaments.

Also of note.. photo cells are extremely sensitive, so the sensor and flicker bulb need to be enclosed in a completely light-proof enclosure to really work properly in this manner