Enough Light? - VL 440

[dpgiffin]

Hi -

I'm looking at putting 2 VL 440s in the audience on Truss. They are about 75' away from the stage.

Based on this table:

From Vari-Lite - Philips Entertainment

Do you think i'll have enough light to light a person at 15* from 75' away?


Ive never learned nor had to use the science of Lx, lumens, and candela, and would like a bit of a crash course if someone could give me one?

Thanks in advance

 

[jglodeklights]

You're going to have a big, dim circle of light. At that distance you're looking at an 19' wide field or so. Even 700watt ML's will be a bit weak at that distance unless they are fitted with a 10 degree or smaller lens.

 

[dpgiffin]

You're going to have a big, dim circle of light. At that distance you're looking at an 19' wide field or so. Even 700watt ML's will be a bit weak at that distance unless they are fitted with a 10 degree or smaller lens.

Thanks.

I can shrink the light with the iris, but it won't be bright enough for an effective spotlight?

 

[derekleffew]

From CB's collaborative Article Mathematical Formulas for Lighting :

Foot-candles = candela / distance in feet * distance in feet

and

Beam diameter = distance * (2 * tan (beam angle in degrees / 2))

thus yields the following table:

Now, there are many other factors to consider when determining whether or not 49 foot-candle s is "bright enough". (As for the "crash course," see Footcandles and Lux , ignore items 4 & 5 for now.) I included field angle pool diameters as I think that may just as important an issue. Can you deal with a 20' circle and no ability to apply any beam shaping (other than iris)? I'd also ask you to consider if 75' away from the stage is optimally the best position for the luminaire s, given the (assumed to be) low angle of elevation ?

EDIT: Posted simultaneously with the above.

I can shrink the light with the iris, but it won't be bright enough for an effective spotlight?

As a followspot? What will it be completing against? (How much other stage light?) By comparison, an Altman Comet (an oft-recommended spotlight around here) at 75' gives 142 FC using a 360W, 82V incandescent lamp.

 

[Senorfish]

That's a moving light too.... the farther away it is the less precise the the position control is going to be. I doubt even 16 bit position control wouldn't have big jumps in one step of position adjustment to the next.

But just like jglodeklights said, you need to look at 5-10 degree lenses for whatever light at that distance.

 

[dpgiffin]

Thanks all

The distance is actually 60' and would be about 14' above the stage. So no, not an ideal situation

Our auditorium is short and long. I wanted to put these two fixtures on our foh but I don't trust the weight rating and the pipe rotates easily enough on its own!

I'm just trying to throw out other ideas to make it work

 

[Janak Jha]

Not at all enough light. look at the VL 770 or 880. same fixtures with more output

 

[Wood4321]

Not at all enough light. look at the VL 770 or 880. same fixtures with more output

Still though, The zoom is the real problem, it only goes down to 15 degrees on that range of fixture. That 20' circle still isn't going to be bright enough I would think.

For that distance the only fixtures I would suggest as a followspot is a VL3015LT (6 Degree zoom), or perhaps a Mac 3 (zoom still a bit large, at 11.5 degrees)
Both also use 1500 watt lamps, and will be bright enough for your needs.

You also might be able to get away with a VL3000, (10 Degree zoom, and 1200 watt lamp) 13' Circle @75' However YMMV.

That being said, these are worlds away price wise from the VL440.
Then again A Used VL3000 should be competitive with a New VL440 price wise. Probably a bit less even.

 

[bishopthomas]

And if you're looking at the VL3000 you might as well include the 3500 and get shutter control.