Foxfury Nomad??? Lumens value but no distance scale? how bright is it?!

[themagickite]

I'm looking at the foxfury nomad, which is an LED work light with a brightness of 4000 lumens.

My question is: How bright is that?

Lights designed for film use always give the brightness in lumens or foot candles matched to a distance in feet or meters away from the light.
this makes it pretty easy to compare them, but I can't work out where the nomad comes in with its 4000 lumens......

any opinions on using LED worklights like the nomad or the pelican models for film use? I'm pretty sure I'd have to gaff on a gel to warm the colour temp down a bit, they run at 6500k, any other considerations or general comments?

cheers

 

[Moseph]

I'm guessing that the footcandles would all depend on the beam angle. From what I've seen, all lumens really is good for is comparing one lamp to another, but actual lighting instruments will take that lamp and direct the light one way or another.

Considering that the lamps that a Diva takes are rated at 2800 lumens, this probably wouldn't give you that much light once you gel it down. Another thing - they'll probably have a green spike in the output, in which case regular CTO won't do the trick. I've found that LEE 108 and 152 are pretty good in terms of a warm and minus green filter (I use 152 for my on-camera LED light, brings it down to about 3700°K), but again, they do cut the output a decent amount.

 

[j1clark@ucsd.edu]

I'm looking at the foxfury nomad, which is an LED work light with a brightness of 4000 lumens.

My question is: How bright is that?

Lights designed for film use always give the brightness in lumens or foot candles matched to a distance in feet or meters away from the light.
this makes it pretty easy to compare them, but I can't work out where the nomad comes in with its 4000 lumens......

any opinions on using LED worklights like the nomad or the pelican models for film use? I'm pretty sure I'd have to gaff on a gel to warm the colour temp down a bit, they run at 6500k, any other considerations or general comments?

cheers

You would have to know the 'solid angle' of the beam of your light, in steradians, which allows one to calculate out the lux, given the lumens and distance form the source.

Here is a calculator for lux <-> lumen.

http://www.ledrise.com/shop_content.php?coID=19

For example.

Given a lamp with 4000 lumen output, a fixture that has a 45 deg 'view angle', at a distance of 2 meters, yields, 2090 lx, which is about 200 fc, given the approximation of 10 lx = 1 fc.

Same setup but 65 deg 'view angle', yields, 1000 lx, which is about 100 fc.

Just looked up the light mentioned... indicates a 8 deg spot and a 120 deg 'space light'.

For 8 deg. gives 65536 lx which would be 655 fc.
For 120 deg. gives 318 lx which would be about 31 fc.

A couple of notes. I found this calculator online, so I don't know how accurate it may be...
LED lights have spectral 'quality' issues and usually in addition to light output, the CRI Color Rendition Index is used indicate how 'good' the spectrum is, a CRI of 95 is suggested for film making, unless a special look is desired.

I personally think shooting with a mind for B&W output is one solution to the 'color' problem...