Continues lightning question

[Anonomatos]

Hi there,

I've been researching lot's about LF recently and I have a question considering continues lightning (I don't really like flash when I'm composing my shot). I'll be shooting portraits in daylight.

There are always big and bulky (and power consuming solutions) as far as I've seen irl and on the net. I'm thinking of building a small and lightweight 'spot' which consists of a rechargable battery pack and 10 watts of Luxeon 5500k LEDs jammed in a small packed with a tripod mount. With my calculations it should last for half an hour or so on a single battery pack.

Any of you have experience on such a portable 'spot' (building and/or using)? Are there any downsides to continues light (compared to flash)? Any tips when working with continual light?

Thanks

*edit*
I've worked with reflection-screens (white and silver) but I'm looking for a constant light source, I don't want to be dependant on the sun or other people holding reflection-screens.

[Bob Salomon]

How will you ensure even coverage from edge to edge and ensure correct color temperature across the field?

[Anonomatos]

Well, 5500k is the basic temperature and a few warmer and cooler (6500k and 4000k) LEDs with adjustable levels will make the temperature exact. This way I can adjust the temperature exactly the way I want (nice for effects, and I won't need color filters for the lights). Though I need an external light-temp-meter.

And what do you mean by "even coverage from edge to edge"? The dividing of the light vs. a beam of light? Or something else?

[Bob Salomon]

Keep the amount of light on the edges the same as the center.
Kaiser makes a LED camera light that has 19 "white light" LEDs that give out about 15 Lux at 3m. It runs for at least 3 hours on 2 AA cells.

This is enough light for a point and shoot camera or a small VCR but no where near enough light to get a large format camera to f11 to 22!

The normal problems with continuous lighting (tungsten or quartz halogen) are:
1:heat
2:bulb life
3:color temperature
4:current draw
If you use professional quality flourescents (HF type) you get:
1:daylight or tungsten color balance, depending on the tubes
2:cool burning compared to tungsten or quartz
3:low current draw
4:long tube life

Until the eveness of the illumination and the output and the color temperature can match flash LED technology is not the answer. A good flash gives a range of outputs down to as low as 1/32. It may have constant flash duration and constant color temperature at all power settings. You get lots of flashes off a modern power pack, you can have dead accurate modeling lights, you get extremely long tube life. And you may have to carry 3KG of weight - including the battery pack - which is really not a lot!

And half an hour of shooting time is really very, very little with large format shooting!

Some very good, portable flash lighting is made near you in Cologne, right by the airport outside Porz or Ferdiand Porsche Strasse.

[Frank Petronio]

Movie makers need high output constant lighting that can overpower existing light... but those lights come in large trucks, requiring electricians and a crew.

You might want to try renting some HMI lights before you go too far.

[Bob Salomon]

[QUOTE=

You might want to try renting some HMI lights before you go too far.[/QUOTE]

Those are not the most portable either compared to flash. Or the lightest or the coolest operating.

[Drew Wiley]

I have never had an issue using old-fashioned Arri and Omni hot lights. You can do it
directly, like an old time movie, or diffuse the light through fabric or polyester sheets.
Color balancing with gels is easy, and the whole system is both portable and relatively
affordable. If color balance is really critical you can use a color temp meter and
correction filters, but this is seldom necessary. Maybe not the best setup for product
shots of ice cream. But for people you just use your assistant temporarily for a fill-in
before posing the subject under the light, or have the main subject relax a minute with
the light bank turned off before the final shots. This is how they did it for decades.
I really like the combination of hot lights and 8x10 film. The subject takes it seriously
and cooperates because they know you're doing it the old-fashioned "hard" way.
I've never even bought a flash system, though that might be nice for uncooperative
kids or something, in which case my own answer is a handheld Nikon instead. This
might not be the right approach for everyone, but I'm sure glad I didn't make things
any more complicated than necessary. The focussing Arri beam is especially versatile.

[jamesklowe]

..you're going to need a lot of kick to light your models at full daylight. You should work backwards, start with what kind of power source do you have? they draw alot of power, i'm not sure what houses are like over there, but you can run about 3 x 2k blondes off 1 house in new zealand (3 circuits, each circuit takes about 3k).

if you don't want to go daylight and shoot with tungsten film, PAR cans give alot of kick for just being 1k.

otherwise if it is daylight you're really after. HMI's are your best bet. downside is they usually charge for bulb time aswell.

all of this is not so portable unless you want to drag a generator around.

[Sideshow Bob]

Is this what you are thinking? Do a search for

1000 LED Video Studio Portrait Panel Light

on eBay. They also have a 500 LED light.

Gale

[jamesklowe]

LED brick lights don't give nearly as much kick as you think they will..

fantastic upclose. but don't bother for anything else. esp. in daylight