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Lights and the phantom


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#1 Fredrik Backar FSF

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Posted 30 October 2007 - 03:45 AM

HI!
Had a discussion in the HD forum about the phantom and flicker with HMI´s a while ago.

Have now completed two productions on the european 230volt 50Hz net with HMI´s and not experienced a single flutter of a light even at 2000fps.

Seems like the 60Hz net in US is a problem somehow even as the flicker free setting should produce a square wave at that hertz too...

One could though with the internal monitoring system of the software detect a slight pulsing change to the red and green channel (blue was totally stable). This was however to way too slight to notice on screen by eye at all.

Well, now you all know any how :-)

All best!

Meanwhile have a look at the IKEA phantom commercial at
http://www.magnoliaagency.se/portfolio-fredrik-backar

(tungsten)
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#2 Mitch Gross

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Posted 30 October 2007 - 11:46 AM

Interesting. I would have to say that others have had problems and I've seen it myself. I'm glad you had success, but I would not generally reccomend using HMIs when shooting high speed.
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#3 Elhanan Matos

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Posted 06 November 2007 - 09:48 PM

Were you shooting interiors or exteriors? How far away were the lights from the subjects? What HMI globes were you using? Were you using any Diffusion? If so How much?

There are plenty of ways to get away with using HMI's at high speeds, but it's usually just not worth it.
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#4 Chris Haring

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Posted 22 November 2007 - 03:56 PM

hi there,
the tvc you can find under the link below was completely shot in HMI (50Hz) and we had no problems with flickering at all. we shot between 500 & 1000 fps.
the main lights being used were 6x18kw arrimax, 4x12kw par and 6xkw par.
all the best,
christopher

http://www.ch71.de/p...ation_Sport.mov
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#5 Rob van Gelder

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Posted 01 February 2008 - 03:57 AM

Here in Thailand, we have 50Hz too, but also see the flicker, or better, the moving arc projected on backgrounds.

But for sure you used the right lamps, the bigger the better and in general, the problem is less to nothing with 6K and up.

We've seen flicker with 4K Arri X and smaller lamps.

My personal belief is that the chips seem to be more sensitive to small variations, or that the software used is enhancing the minimal changes in light to a level that it can be seen, where as film is more "stable" and forgiving.
But I have no proof of this though.

Frequently I work with Photosonics technicians and while they have mentioned particular Photosonics-cameras related problems, in general they do not see that "moving arc" effect or the slight color changes we see with chip-based cameras.

Im' looking further into this...... <_<
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#6 Rob van Gelder

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Posted 01 February 2008 - 04:01 AM

One question:
is anyone using DC-powered lamps with High-speed filming?
As smaller lamps are often showing that the glowing filament has a variable output due to the 50/60Hz, I consider making a DC-distribution box with some heavy 3-phase diode-modules.

And this only for Tungsten lamps, of course!

I wonder if anyone has done or worked with that before.

Rob
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#7 Kevin Zanit

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Posted 01 February 2008 - 05:12 AM

I know of a few instances where people have used DC power fairly recently. Trouble is, its fairly hard to find good DC power, I know Universal still has DC, and I have had DC/ AC generators, but I have heard mixed reviews as to how reliable DC power from a generator is.

Kevin Zanit
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#8 John Holland

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Posted 01 February 2008 - 12:03 PM

i know over here DC just doesnt exist anymore which is a great shame .So cant power Brutes anymore ,thats if you can get the carbon rods to start with .
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#9 Dane Brehm

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Posted 10 April 2008 - 06:50 PM

What kind of speeds are we talking here?

I did 800fps shoot a few months back and didn't have a flicker issue?

Dane Brehm
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#10 Mitch Gross

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Posted 11 April 2008 - 12:24 PM

I was on set last week on a shoot where we did plenty of 300 & 500 fps and a little 1000 fps on Phantoms. We had tungsten including a nine-light, square-wave HMIs and a Xenon. No visible flicker. The possibility for flicker is just that: a possibility. Some times you never know...
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#11 Donavan Sell

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Posted 16 June 2008 - 05:39 PM

When I used the Phantom we were in the 800-1k fps zone and I noticed a significant amount of flicker from the nine lights and dino we had.

I was told from Vision reserch that the best to use was a single filament bulb tungsten to avoid flicker issues. ( personally i didnt think it would matter) but after lighitng and watching playback we saw significant flicker. swithced over to a single filament 10k and all was good.

So just something to think about when putting in your lighting order for a phantom shoot.
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#12 Kevin Zanit

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Posted 16 June 2008 - 06:56 PM

The HMIs tend to be more hit or miss with the flicker (they tend to work fine).

With tungsten, at the higher frame rates on AC power, you will always get flicker from units smaller than a 5k.
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#13 Todd Davis

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Posted 05 December 2008 - 02:48 PM

Why does flicker show up on the Phantom using small wattage incandescent lighting while the same lighting used at the same frame rate on Photosonics does not show flicker?
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#14 Kei Yokokawa

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Posted 11 February 2009 - 07:39 PM

I just finished a TVC shoot with Phantom HD. I was a tech on set and had "Revolution Lens system" (similar to Fraser Lens) on the camera with max speed of 1000 fps.
We had 3 x 18K HMIs, 2 x 12K HMIs, 2 x 6K pars running all at once to get enough T stop and we did not see flickers. It looks like it cancels out each other with all these lights. ( still flickers with single or two lumps)
Tiny vibration could be seen through the blue phase only but it was not big enough to be a problem.
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#15 JA Tadena

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Posted 01 March 2010 - 10:26 PM

I just finished a TVC shoot with Phantom HD. I was a tech on set and had "Revolution Lens system" (similar to Fraser Lens) on the camera with max speed of 1000 fps.
We had 3 x 18K HMIs, 2 x 12K HMIs, 2 x 6K pars running all at once to get enough T stop and we did not see flickers. It looks like it cancels out each other with all these lights. ( still flickers with single or two lumps)
Tiny vibration could be seen through the blue phase only but it was not big enough to be a problem.


Thats very interesting. Im using the Phantom HD next week on exteriors and we plan to shoot 1000fps. I''ll have an 18K, 12K and 6K on set. I hope it does not show any flicker. This is the first time I'll be using HMIs for the Phantom HD although I'm planning to use available light if necessary. Is there anything else I have to watch out for? Thanks
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#16 JA Tadena

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Posted 10 March 2010 - 12:30 PM

I finished shooting using the Phantom HD at 1000fps. I did not see any flicker using the 18K flicker free with a DC generator. I only used the 18K once since most of the shots were available light.Thanks

Edited by jatadena, 10 March 2010 - 12:32 PM.

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#17 John Sprung

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Posted 10 March 2010 - 06:43 PM

but I have heard mixed reviews as to how reliable DC power from a generator is.


DC if it's from an alternator or rectifier would be no better than AC running small tungsten lamps. It needs to be filtered with big capacitors.





-- J.S.
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#18 John Sprung

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Posted 10 March 2010 - 06:47 PM

Why does flicker show up on the Phantom using small wattage incandescent lighting while the same lighting used at the same frame rate on Photosonics does not show flicker?


Same subject matter? It would be interesting to do a side by side test. My first guess is that busy subjects may tend to hide the flicker, while large even mid tones with no motion would tend to reveal it more.





-- J.S.
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#19 Hal Smith

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Posted 14 March 2010 - 11:58 AM

DC if it's from an alternator or rectifier would be no better than AC running small tungsten lamps. It needs to be filtered with big capacitors.


Full wave rectified DC from a three-phase AC source has about 6% ripple as opposed to full wave rectified single phase with 100% ripple.

Full Wave 3-phase Rectification (See Page 257).

If you need pure DC it takes a lot less filter to clean up rectified three phase because of the much better peak to crest ratio plus (for 60Hz power) you're filtering 360Hz ripple, not 120Hz ripple.

I looked into producing commercial three-phase DC power supplies for on-set use but couldn't quite make the economics work so I dropped the project. I was using a design goal of 120 volts DC at 400 amperes. Biggest problem was cabinetry, I could put a bare bones supply together without too much cost but boxing it up so that it could take rough and tumble set abuse was E-X-P-E-N-S-I-V-E.
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