HMI Balloon Light

Micah Kovacs · October 6, 2009

I have a short coming up and I already have a 4k HMI balloon on reserve for two night scenes - the only problem is I have no idea what to expect from it.

I'm most concerned about the output, because I saw some photometrics of a 4.8k that only gave 2.8 fc when it was 50 feet high and 50 feet away. Because we're shooting on the Red, I'm hesitant to boost my iso for fear of the grain - I wouldn't go higher than 500. So is this the kind of output I should expect?

What about wind? is a light breeze a major problem?

and how about the helium? Does it take a lot and how expensive will that be? (we don't even have that budgeted yet)

If I just want some general moonlight, would I be better off putting up a 2.5k fresnel?

Thanks in advance!

John Holland · October 6, 2009

If you are thinking of the 4k balloon , and maybe not go for it [they are expensive ] why only then thinking of a 2.5 Hmi , and not a 4k Fresnel ?

Micah Kovacs · October 7, 2009

If you are thinking of the 4k balloon , and maybe not go for it [they are expensive ] why only then thinking of a 2.5 Hmi , and not a 4k Fresnel ?

Well, we already have 2 2.5ks in the budget, along with 2 1.2ks.

I suppose I could swap out the balloon light for a 4k. But the highest stands I have are mombo combos and that only gives me 26' of height. I don't think I can squeeze a two day condor rental in there.

So is the output really that poor then?

Tim O'Connor · October 7, 2009

Well, we already have 2 2.5ks in the budget, along with 2 1.2ks.

I suppose I could swap out the balloon light for a 4k. But the highest stands I have are mombo combos and that only gives me 26' of height. I don't think I can squeeze a two day condor rental in there.

So is the output really that poor then?

I would double check your photometric table. 2.8 footcandles is really low and doesn't sound right to me. What lights?

Brian Glassman · October 7, 2009

Check out Airstar's website, specifically http://airstar-light.us/film_lighting.html and download the Film & TV Catalog; pictures of the balloon lights are in there along with photometric readouts. The 4.8K HMI at 50' high & 50' away foot candles come in at 5,11.

As far as wind goes, the elliptical 4.8K is pretty resilient in the wind as I've operated this in 22 mph winds at the Atlanta Speedway - down drafts are another story. Get a good tech that knows what they're doing.

Helium pricing does vary in different parts of the U.S. check with Airstar to see if they have any connections in area.

Tim O'Connor · October 7, 2009

Check out Airstar's website, specifically http://airstar-light.us/film_lighting.html and download the Film & TV Catalog; pictures of the balloon lights are in there along with photometric readouts. The 4.8K HMI at 50' high & 50' away foot candles come in at 5,11.

As far as wind goes, the elliptical 4.8K is pretty resilient in the wind as I've operated this in 22 mph winds at the Atlanta Speedway - down drafts are another story. Get a good tech that knows what they're doing.

Helium pricing does vary in different parts of the U.S. check with Airstar to see if they have any connections in area.

Good link. Yeah, that's not a lot of light, about as much as a streetlight, although it is

a good amount of light if it's taking a scene from total darkness over a wide area.

Do you have to be 50' away and 50' high? At 50' high and 20' away you get 13 footcandles and that's enough to get a T2 at 500 ASA. Could you come lower and closer?