Lighting up an underground football field with no electricity... HOW???

[Leszek Vogt]

A battery powered flood light would be great... is there such a thing?

Lars, most of the larger cities will have pro video rental place (and they carry such)....you should be able to find something there that works.

Les

[Tin Can]

These are new, reviewed in Shutterbug mag, I have no experience with it.

http://www.bhphotovideo.com/bnh/cont...=REG&A=details

[gleaf]

Many of the continuous light studio LED arrays have a 12 volt DC option. For example:
http://www.bhphotovideo.com/c/produc...35w_AC_DC.html
Should be many similar light systems available in the portable construction industry lighting these days.
May be enough variety for you to decide which light will provide the characteristics you desire rather than letting the light source dictate the art.

[photonsoup]

these look like just the thing for your project http://profoto.com/b1
looks like there are a lot of places that rent them around the world

[mortensen]

@ Dave: Great result! Inspiring to see, what you managed to get out of light painting - no spectacular drop shadows and an impressively even illumination. Serves as a good example.
@ Les, Randy, Gleaf & Photonsoup: Thanks for good suggestions - I'll note 'em all. I looked at the Lowel GL-1 the other day and my local rental place stock anything Profoto. I am quite sure that I will opt for a continuous, battery powered light source.

Now I 'just' have to execute it properly...

[Jim Jones]

Long ago I photographed an underground WWII room that was constructed like Mortensen's reservoir, but much smaller. An ordinary strobe, open flash, and Kodachrome 25 sufficed. Exposure was calculated from the guide number. The strobe's reflector reduced hot spots on the floor. The columns were wide enough to conceal me from the camera. A low power flashlight shielded from the camera made navigating in the totally dark room easy. It took maybe half an hour and the entire charge of a weak strobe battery. Alas, the transparency is long lost. For the huge reservoir, raising the flash on a pole to perhaps midway to the ceiling would help eliminate hot spots. A small wide-angle reflector might provide the most even lighting. Several flashes at various angles from behind each column would fill in the sharp shadows. You might want to bring your lunch and a powerful external battery.

[mortensen]

... thanks, Jim - good with a thorough explanation of method! I see your point with being behind the columns

[Brassai]

I work at night, mostly, and light up big stuff. My subjects are usually fast moving trains and I have to use flash to catch them. Your subject is not moving, so all of the suggestions above would work. If you have unlimited access, I would start with the big floodlights first as they are the cheapest way. Remember effect of light fall-off, that as you double the distance you have to double the exposure. The room with all the pillars will be the hardest because there will be shadows. I would try lining up either flash bulbs or battery powered flash along one side wall, to keep the light going in one direction perhaps. Another thought would be to place the flash behind the pillars and fire them away from the camera. You could do this with relatively small flash by making multiple exposures and moving the flash. Wide angle setting or reflectors, of course to diffuse the light into a larger area. I don't think you need big monolights and battery packs for this, and they would be the most expensive method anyway. The trick here is not so much having a lot of power, but rather keeping it even. Below shot done with x5 White Lightning monolights (~6,000ws) plus x8 Nikon SB-25 flash units. Train speed was ~20 mph. To get a sense of the scale, notice the red tractor in bottom left corner.

[mortensen]

Thanks, Brassai - what you and jim suggest about standing behind the columns, firing away from the camera is what I find to be the most promising systematic approach. I'll post, when it is done (that means give me a couple of months )