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Strongest Point Source

class="Body">Looking for the strongest tungsten "shadowmaker" around. Needs to cast hard shadows a mere 10 ft. from a miniature airplane (backlight) with most footcandles possible so I can overcrank too.

class="Body">Would a 20K with the fresnel swung open be the strongest point-source ?

class="Body">Any other suggestions ? Mole-ipso ? Molebeam projector ?

class="Body">Mark Doering-Powell


class="Body">Pretty sizeable filament area for "point" source. A 12K or 18K HMI with clear glass and 85 filtration should be stronger, although the arc shape might not give as nice a shadow. But it seems like it would be less likely to fry the "talent" than that 20K, which produces 80% heat and only 20% light!

class="Body">Wade K. Ramsey, DP Dept. of Cinema & Video Production Bob Jones University Greenville, SC 29614


class="Body">Is it possible to shoot outside??? If so I know of a big light that does very nice with hard shadows and can be had for next to nothing.

class="Body">Or another idea would be to have really crisp shadows done in post. >From only ten feet it will be a bi.... to try to get really crisp shadows. Distance of the light source is the key here.

class="Body">Good luck

class="Body" Daniel Villeneuve, c.s.c.

class="Body" Directeur-Photo / Director of Photography

class="Body" Montréal, Canada

class="Body" http://www.aei.ca/~davil


class="Body">Mole Richardson has a new version of a very old light projector, called a beam projector, that uses a parabolic mirror. This is the most powerful tungsten lamp available that I know of.

class="Body" Roy H. Wagner ASC

class="Body" Director of Photography


class="Body">Mark,

class="Body">as you probably know a mirror will sharpen up the source. (we talked this over once before -its in the selected archives on the site.)

class="Body">somehting i've never done and am curious about is to double or triple reflect a source to see if that firms it up even more. it _should_ work and maybe will help you in that limited space.

class="Body">good luck with it. let us know.

class="Body">caleb changing careers intransit


class="Body">Try a 4K GOYA HMI unit with the black reflector. This unit is an openface [well, with a safety glass] and with the black reflector installed, is basically a single point of light. Of course it's a daylight source, not 3200 degrees, but with a 4K worth of light to play with, a 4'x4' open-frame with full CTO should not be a problem!

class="Body">Cheers,

class="Body" Jeff Barklage, s.o.c.

class="Body" http://www.barklage.com


class="Body">Well, you may not like this, but... The strongest point source you can have in tungsten is probably going to be a Mole Brute-arc (225amp DC arc with the electrodes feeding at an angle to each other) with a plain (and plane) glass instead of a fresnel... ...and yellow flame carbons. If you are using it inside, you may have to run stovepipe to an exit as it spews a nasty cloud of gas, but I cannot think of any sources that would be as sharp for the same amount of light. A 20k is not too bad, but the filament array is relatively large. I have not used the mole Beam spot projectors, but having used their forebears in theater extensively (they were what was available for the ole' shafts of sunlight before PARS got into theater) while they give relatively parallel rays, the apparent source is the size of the reflector, not the filament, with the result that you would have fairly sharp shadows if the proportion of the distance between the fixture and subject is high relative to the distance between the subject and the surface on which a shadow would be falling, but in the case of miniature work, I think they may be too large. Moleipso's are just plain crap. I recently put a 2k Moleipso next to a Source 4 (575 watt tungsten) just as a reminder and I got more than double the light and a cleaner beam from the silly little source 4...there is something to be said for a 30 year advance in optical engineering. I don't think you will get what you need from a Source 4 You might also want to try a Xenon Super Trouper followspot at some decent distance (here is where you might want to use a mirror) corrected for tungsten. Becase it is a combination of adjustable lens train and parabolic mirror, you can get the beam to focus efficiently at sufficent distance that it will be effectively a point source. The 2500w. HMI follow spots that might tempt you do not have enough poop to do what you want. You could use a big Xenon corrected, but you will have to get it pretty far back (directly or with mirrors to get the nice sharp shadow you want.

class="Body">Mirrors do not intrinsically sharpen things - the increased distance that they allow decreases the apparent diameter of the source...if you put up a 12" china ball, the further away you walk from it, the harder it gets because the fewer degrees of your viewing angle it covers - the smaller it appears as a precentage of your world - I can't seem to get this concept into english, but I hope someone gets what I mean - A mirror works that way, but it only helps if you use it to move the light further away...and the inverse square law DOES apply to light that is reflected in mirrors. (If you are about to mention that it doesn't count with the sun and reflectors, ...it does, it's just that compared to 93million miles, 25 feet more or less thanks to a reflector is a very small precentage change)

class="Body">Note: Both the Brute-arc and the Xenon super trouper and other xenon fixturesare DC and will suffer over-cranking with no flicker problems. That said, yellow flame carbons can be a bit sputtery -make sure you have an electrician who has actually run arcs before. (call for recommendations if needed)

class="Body" Mark H. Weingartner

class="Body" Lighting and VFX for Motion Pictures


class="Body">I was going to mention this, having used Goyas a bit ...They are basically a modern version of a fixture called an Olivette that harkens back to early theatrical lighting... ...but I did not mention it because I recently used one for exactly this effect (corrected 1/2 way to tungsten) and was completely underwhelmed by the output. Since you are not using a reflector, the light you get is limited to what comes off the arc in the direction you want it...and 4k just ain't enough You would do better with a 12k or 18k with clear glass backed further away...depending on what size you want your shadow with respect to the size of the miniature. If you have the luxury of ordering more than one toy and returning the ones you don't want, grab a Goya, by all means.

class="Body">Good weapon to have in your arsenal, if not for this shot, for another one some time

class="Body" Mark H. Weingartner

class="Body" Lighting and VFX for Motion Pictures (Woodland Hills right now)


class="Body">Mark,

class="Body">Your previous post on hard point sources was excellent.

class="Body">But I would like to make a further point about the use of clear lenses verses fresnal lenses to achieve a sharp source. In my experience, which I've posted when this subject was previously discussed, I've found that there is a consideration to be made for each approach. The clear lens is definitely sharper but the loss of output from the missing fresnal usually means pushing the light in closer to achieve the desired maximum foot candles. This defeats the purpose of the clear lens as the source gets softer when the light moves closer to the subject. I've found the same holds true for the fresnal lensed lamp. As it is moved further from the subject, it gets harder but intensity is lost.

class="Body">The result I found is that there isn't much of a considerable difference between either source if output is a real concern. To get the same shadow from either source with the highest footcandle output, it doesn't really matter which lens is used.

class="Body">The clear lens does have a wider spread so that it covers more set area. This makes it particularly useful for that purpose where it would be impractical to move the fresnal lens back far enough to produce the same sharp shadow. But be prepared for the much lower output.

class="Body">My 2 cents.

class="Body">Jim Sofranko NY/DP


class="Body">Thanks for all the suggestions... they were all very useful.

class="Body">On the shoot that prompted my inquiry : -can't go day/ext for lots of reasons: its a night shot, Milo's on stage, wind could affect model... -flamearcs scare me because I've never used one (though I'm burnin' to) and the occasional flicker could really hurt at various fps for sillhouette/matte passes and smoke/atmoshere passes -Xenons and molebeams will only work through a mirror since the bluescreen's a mere 15 feet away... or I might be able to raise the screen and come from behind for that pass.

class="Body">Really need combination of fc and sharpness since I'm trying to achieve a backlit 25:1 AWACS model (6 ft. width) with smoke atmosphere to get some rays-o-smoke. Cannot deal with another hermetically sealed smoke chamber to undercrank the atmosphere and avoid dancing fog, so I'm left with overcranking it a bit and try to get the smoothest smoke possible on a large stage... I'll even sacrifice some DOF. I'm hoping it's just a luminance/additive matte but then again those are the most critical to nail (what a quandry). It'll be my last pass to let the stage vent for next setup.

class="Body">I'm entertaining the idea of a clear-glass 18K HMI and melting a Full CTO and red/orange gel (don't ask) in front of it... or maybe some F-250D to lose the CTO. Possibly into a 4x4 mirror. I'm looking into a Sunray or Arri unit. What's the best model I can try to scrounge up if I could pretend that money were no object ? Any specific vendors to recommend for rental ?

class="Body">Mark Doering-Powell West Hills, LA, CA, USA, Earth...


class="Body">Hey, how about one of the old carbon arc searchlights? The kind that comes on a truck (an old pickup, I think) w/ its own generator. There is a company in L.A. that has about 6 or 10 of them and I saw one at the Egyptian Theatre a while back. It's, uhhhhh, sort of a big source, but the beam is parallel. I believe there was an old arc lamp called the "Sun Arc" that was like thay; but where would that be?

class="Body" Mac

http://people.we.mediaone.net/chuck110


class="Body">As ususal, Jim is right on the money. I was looking too much at the shadow edge and not as much at the output. That is, of course, why my first and still hottest suggestion might be the Brute, but Jim's description of where you end up in the hardness/output continuim is quite true. The fresnel, after all is a device that is stuck in front of the fixture to cheat the inverse square law (which it does) if you make the light rays more parallel, it is as though the source were further away, so distance changes are as a proportion of a longer distance than is actually the case. the smaller the details on the shadow-throwing subject, however, the more likely that the size of the fresnel is significant enough to affect softness of the edges of the shadow, so you end up having to back off enough to make the apparent size of the fresnel as small as possible. It really depends on the specifics of the shot whether you end up doing better with the fresnel or the clear glass. For safety reasons, you DO NEED THE CLEAR GLASS with HMI's!!!!!!

class="Body">And while 10k and 20k bulbs are less likely to explode catastrophically than enclosed arcs are, in sensitive situations ou should use a clear glass in front of them too. I had a lowly little Blonde explode it's little 2k bulb once, and the hot shards of glass immediately started burning through the rug at the talent's feet. Imagine that hitting someone's exposed skin.

class="Body">Of course we know we should but I have almost never seen clear glass in front of tungsten fixtures. when used "door open."

class="Body" Mark H. Weingartner

class="Body" Lighting and VFX for Motion Pictures


class="Body">If your beauty pass is in smoke and you can get the soruce wide enough, I would keep the fresnel - the output will be more important Forget the Goya - insufficient horsepower I think the xenons would be more trouble than they are worth for this, rig-wise. If your are doing your matte pass against blue, I would still try to pull the effect light towards tungsten as opposed to going with the daylight film because you will get better chroma separation between the screen and the subject that way (if you are lighting the screen with blue bulbs)...if you need to - See what the post folk say - hard plane skin etc maybe they won't care as much and the extra stop (and DOF ) helps them more... also depends on how much motion blur.

class="Body">Mirror only if you need to for distance - once you smoke up, the area between the lamp and the mirror will be both a secondary source that needs to be flagged off, and a light attenuator...and that whole area will glow more than the rest of the stage even if you flag it.

class="Body">The more I think about it, the more it seems you will end up keeping the fresnel in for the beauty - smoke pass. Are the critical shadows the ones cast IN the smoke? Consider having a lot of blacks around to kill as much scatter as possible outside the frame which will heighten the contrast in the smoke of light vs. dark Sounds like fun - when are you shooting? Another thought - If you have the time and money, which you never do, consider doing two smoke passes - if you see swirling (localized density differences changing with respect to time) you can paint through a precentage of the "other" smoke pass to minimize the swirling. That way the "paint through" smoke pass would still preserve the shadow areas caused by the model. What the hell, it's only another few minutes and another few feet of film Good luck

class="Body" Mark H. Weingartner

class="Body" Lighting and VFX for Motion Pictures


class="Body">Not only because of explosion, but because of UV rays from the TH lamp. Years ago I had an assistant who received an unexpected sunburn from spending most of a day wiggling a hula in front of an open 10K lamp to make flickering firelight. And he was behind the reflector.

class="Body" Wade K. Ramsey,

class="Body" DP Dept. of Cinema & Video Production

class="Body" Bob Jones University Greenville, SC 29614


class="Body">One time I recall trying so hard to get a sharp window pattern with a rain FX on a wall with lights outside aiming inward toward various windows. Always a difficult FX to achieve. All the usual logical lamp choices were just too soft even backed way off but a light did manage to create the FX. It was a 6K par aimed toward another window and backed way off. But the side flag on it moved and the slight edge of the lens peeped into the adjoining window. That worked great!

class="Body">I don't know if that will help but at the time it created a really hard source. Just like when you see some aberrant spill from the housing of a lamp creating a weird pattern on a wall somewhere. The output is never high but it sure is a hard source.

class="Body">My advice is to try a few very different approaches and see what works best for your specific needs.

class="Body">Best Regards,

class="Body">Jim Sofranko NY/DP


class="Body">Mark, you just saved my skin... 2-3 smoke passes are an excellent idea. I've also requested to have Milo and modelmover run at various fps so that I can 60fps the smoke pass since the "swirls" can really flicker at 0.94 fps.

class="Body">I also think that the Fresnel may be too large since the light will be fairly close to the 6 ft. airplane model, so I think 18K HMI clear glass with daylight film will be my choice. It's luminance matte only so the blue/matte pass is already done. We're just trying to get shafts of light at f/22 and 60fps.

class="Body">Thanks again.

class="Body">Mark Doering-Powell LA, USA


 

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