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#1 Fredrik Backar FSF

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Posted 02 October 2007 - 07:56 AM

Hi all!
Used the Phantom HD to great success on an IKEA commercial (see http://www.ikea.com/...gnasovrum.html) mixed with 35mm as opening films.
Used large tungstens on this job in excess of some 500kw in total as flicker becomes a factor
when going down lower than say a 5kw at 2000fps.
Now the question: Who has experience around these filmspeeds with HMI Units?
The phantom delivers full 2k resolution at 1000fps, so I guess that´s where I´ll be Playing.
Anything too low in HMI-terms? Or; are all units safe at "flicker free" as the cycles/second are so high??
Many thanks/Fredrik
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#2 Mitch Gross

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Posted 02 October 2007 - 10:12 AM

You can't trust HMIs because of "arc wander," which is a shimmering effect caused by the movement of a hot spot within the plasma within the bulb. It can vary from different sized units, age of bulb, power conditioning, etc., so it is near impossible to predict.

Nice spot.
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#3 Kevin Zanit

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Posted 03 October 2007 - 12:38 AM

Looks good.

We always use tungsten sources, never HMIs because of the above, the arc wander (and flicker). 5k and up tungsten is the best bet for the most part.

We rarely correct the tungsten sources when working with the Phantom because the RAW files it makes has so much information that we can white balance well in post (for example, see the link in the bottom of my signature).

Kevin Zanit
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#4 Fredrik Backar FSF

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Posted 03 October 2007 - 04:52 AM

Looks good.

We always use tungsten sources, never HMIs because of the above, the arc wander (and flicker). 5k and up tungsten is the best bet for the most part.

We rarely correct the tungsten sources when working with the Phantom because the RAW files it makes has so much information that we can white balance well in post (for example, see the link in the bottom of my signature).

Kevin Zanit


nice films!

So hmi´s flicker even at normal even divisible speeds?
at the 1000fps with the correct shutter set which would be 1 millisecond I experiensed videomotion but as I made it faster the better it got.
Where do you generally end up? Also, to control exposures, do you do it by eye or the lame vectorscope in the software??
On the set of the ikea I had 2pcs wendys as key and some 4pcs 12k fresses through grid as fill and a 12k for back. The video high lights are still a problem I think, so any suggestions on huge source with immense power???
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#5 Fredrik Backar FSF

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Posted 03 October 2007 - 05:09 AM

Hey again, I also shot this far back on the NAC memre cam at mostly 2000fps.
I had a 2,5 hmi in a chimera and some straight 200hmi´s. I had no probblem with flicker on the larger unit, possibly because it was throught the chimera, but the 200s I only got flicker from a few times. Any good links too look this up more on??
All best!
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#6 Kevin Zanit

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Posted 03 October 2007 - 11:07 PM

Thanks,

Through diffusion will help hide the flicker, sometimes to the point of not being able to notice it. That said, I can promise you, money back, when shooting at 1000fps (or even 500) you will get some form of flicker/ arc wander from "conventional" (i.e. not a light made for this purpose) even with flicker free ballasts.

With the Phantom I just use the SDI out on a good HD monitor combined with the histogram in the software to get my exposure. We also have a somewhat proprietary post work flow that maximizes the amount of information we can get from the Phantom, easily approaching if not surpassing that of film's (with a lot of post work, not off the shelf).

Kevin Zanit
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#7 John Sprung

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Posted 04 October 2007 - 02:07 PM

Through diffusion will help hide the flicker, sometimes to the point of not being able to notice it. ....

I can see how it would help with arc wander. But for flicker due to the AC frequency, I don't see how diffusion would help. It spreads photons around over space, not time.





-- J.S.
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#8 Mitch Gross

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Posted 04 October 2007 - 09:59 PM

By the way Fredrik, how did you avoid flicker in the small practicals mounted above the mirror? Were they DC powered? Just lucky?
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#9 Kevin Zanit

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Posted 05 October 2007 - 02:13 AM

Your right, flicker is not the correct term (I am just using it for simplicities sake), arc wander would be hidden through heavy diffusion. Having multiple sources on different phases through diffusion could also help with flicker.
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#10 Fredrik Backar FSF

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Posted 05 October 2007 - 06:43 AM

By the way Fredrik, how did you avoid flicker in the small practicals mounted above the mirror? Were they DC powered? Just lucky?


As all shots were lock off, it´s been done as plates, all the window stuff is green screen :-) Lotsa post work!

BY THE WAY! At the bottom right corner of the frame it says "byt sovrum" meaning change bedroom in english. Click that and get 3 more films.

All best, Fred.
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