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-   -   faking a sun (https://www.dvinfo.net/forum/photon-management/106989-faking-sun.html)

Stephen Eastwood October 31st, 2007 08:51 PM

faking a sun
 
so how much power does one need to fake a sun flare in a shot? my main reason is I would think to bring a 10 k but I have a place that is fine with shooting but no generator, so now I am looking for an alternative, that can run battery powered, I am thinking of trying late day so the ambient would be less (so would time) and trying maybe a 200watt hmi? or what about these multi million candlepower lights? how much light are they really? I could live with a warm glow which may be better overall than a daylight hmi but are they anywhere near enough? I know they last a realistic 10-15minutes per charge but I could have 5 or 6 which is more than the time I would likely have of low sun anyway.

I have found these anyone have any experience?

http://www.nativeoutdoors.com/cyclop...FSasGgodSySpdw

http://www.thegreenhead.com/2007/07/...-spotlight.php

http://www.walmart.com/catalog/produ...uct_id=5839257

Bill Busby October 31st, 2007 09:32 PM

Why not just create the flare in post?

Bill

*edit* I assume you mean lens flare?

Richard Alvarez October 31st, 2007 09:42 PM

What exactly are you trying to achieve? As Bill says, you can apply various 'lens flairs' in post. I use Knoll LIght Factory, but there are others out that will do the same thing.

Stephen Eastwood October 31st, 2007 09:49 PM

I could also have a CGI of the entire video done, but that kind of defeats the point of doing it. I want to have a real lightsource and when its in the shot it should flair, when its not it should brightly backlight the subject assuming it is behind from the camera angle, and look relatively natural.

I have screened off an entire pool and rear of a house to cut light but this is really not that big of a production that I want to bring a 200 foot net to start covering the train tracks and park area so I can use a smaller light just because the location wont allow generators, there must be some way to get a relatively strong light to run on battery power, even if its short lived and requires many batteries. I was more curious how much light was a minimum I could get away with and if using the bright spots or maybe a lower powered hmi would be enough.

Richard Alvarez October 31st, 2007 10:19 PM

Stephen.

I'm still trying to read between your lines of description. From what you've stated, you want a PRACTICAL LIGHT SOURCE that is part of the shot. Something that flares when aimed at the camera, and simply backlights the subject when they step in front of it? What is the light source supposed to be? Why is it in the shot? What is the light source supposed to look like?

Stephen Eastwood October 31st, 2007 10:41 PM

A sun, if its high enough or low enough to be in the shot where needed, and flaring the stand will be basically invisible since the sky itself will be bright, although at spots where I may want it used it would be coming from behind a tree or at least some leaves. Nothing terribly new being done, I have done it plenty before only I had power, now I have a limit on power and would rather not have to scrim an entire large area of park, tracks, and open space. Its possible, but I have a feeling there are alternatives.

Stephen Eastwood October 31st, 2007 10:44 PM

Have I mentioned that strobes and stills are so much easier in general, which is where most of my work has been, only now I am booking 3 commercials a month and scheduled for 4 videos so I am playing some catch up since I like to know and have ideas of how to do something rather than just relying on others to figure it out and then be upset when things may not be what I want.

Glenn Chan October 31st, 2007 11:25 PM

Hmm what about:

A- Using a mirror.
You might need to re-aim it a lot.

B- You can get a Joker HMI that will run off battery power. A larger 1.2k/2K HMI unit can run off the location's power. You'll need good guage extension cables, nothing else on the circuit (esp. don't have people inside the building turn on the microwave or other appliances on the same circuit), and a 20A circuit for the 2k HMI.
I don't know if that's powerful enough (I don't think it is?).

(Sorry if this post is not necessarily helpful since I haven't tried either approach.)

Jim Andrada October 31st, 2007 11:43 PM

For what it's worth, the typical power of sunlight is just under 1.5kw per sq meter of illuminated surface

Maybe something like one of those truck mounted anti-aircraft searchlights you see at outdoor events would do the trick.

Getting enough power to cast a strong shadow in daylight will be quite a challenge I think

Marcus Marchesseault November 1st, 2007 01:41 AM

I like the idea of using a mirror. You can't get that kind of lumens without a big HMI.

Why no generator capability?

Richard Andrewski November 1st, 2007 06:48 AM

It's got to be a small point light, no diffusion on the lens, just a clear lens. I really wonder if one of those super bright flashlights, pointed right into the camera might not produce your flair (late in the day), but I doubt you'd get backlighting on your subjects with one of those though--they're not that strong. You're talking 1200w or larger HMI par for that. If you use a mirror, it'll have to be pretty small or people will see the mirror.

Richard Alvarez November 1st, 2007 08:26 AM

There are two effects to achieve here. The backlight and the flair. WITHOUT having power for a big HMI, I don't think you're going to get the flair. I doubt you will get the backlight, but it's possible if you shade the area enough.

Without actually knowing more about the shot/s and locations and power availablilites, it's hard to give you any better advice. You COULD simply buy one of those lights, aim it at the camera and test it out.

But seriously, have you ever USED a flair effect in post? They are not hard to apply, you can animate the flairs, rotating, extending, turning them on and off at will... choose the size, shape angle and even the LENS style of each flair. Until you have actually seen such an effect applied in post, it might be premature to discount it.

Tim OBrien November 6th, 2007 10:00 PM

One Million Candlepower Spotlight - Rechargeable and only $15
http://www.harborfreight.com/cpi/cta...emnumber=93366

(They use 'em for varmit hunting...)

Jim Andrada November 7th, 2007 01:46 AM

Sounds great, but I doubt you'd even see it in daylight unless it was shining in your eye.


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