How much light am I really going to need. HVX 200a with the redrock.

Jimmy Moss

Jimmy Moss

Well-known member
So I'm shooting a feature witht he redrock HVX combo and I've been wondering how much light I'm really going to need.
I want to make sure I have enough light to run my HVX at f2.8 and the nikon at 5.6 or higher and still get a 50% exposure with a 18% gray card if nesessary.
Obviously it depends on the shoot but I'm thinking of getting tungsten, one 2000w key frenel light with ability to add diffusion and daylight balance and still have enough light at 15-20 feet. Then 3 1000w frenels with same capabilities mainly for fill, kicker, and backgound. I can get that for under $1500 with accessories. What do ya think?

I'll probably add the Cinescreen II for an extra .75 stops of light, so that will help too.
 
Jimmy Moss said:
So I'm shooting a feature witht he redrock HVX combo and I've been wondering how much light I'm really going to need.
I want to make sure I have enough light to run my HVX at f2.8 and the nikon at 5.6 or higher and still get a 50% exposure with a 18% gray card if nesessary.
Obviously it depends on the shoot but I'm thinking of getting tungsten, one 2000w key frenel light with ability to add diffusion and daylight balance and still have enough light at 15-20 feet. Then 3 1000w frenels with same capabilities mainly for fill, kicker, and backgound. I can get that for under $1500 with accessories. What do ya think?

I'll probably add the Cinescreen II for an extra .75 stops of light, so that will help too.
Click to expand...

Here's some "back of the envelope" calculations.

You start with 320ASA for the HVX. Add the M2 and you are at 200ASA equivalent at best. I'll be slightly pessimistic and use 160ASA. You want to shoot 2.8 on the HVX, that's an additonal 1.5 stop. So we normalize for it and set the meter for 50 ASA.

The EV of shooting at 1/48 shutter and f/5.6 is 10.67.

Footcandles = 2^EV / ASA * 0.04. So you'd need about 800 fc on your correctly exposed surfaces.

A 2K fresnel in flood mode (which is what you'll mostly use) gives you about 520 fc at 10'. or 250 at 15'. Add CTB full and you are at about 90 fc. Add diffusion and you're looking at 40-50 fc. If you spot it halfway you get about 200 fc.

In other words. fuggetaboutit.
 
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Just a slight correction.

the M2 adapter (older glass ) loses approximately 1.5 stops. This is prior to zooming in and closing down your camera's iris as well as adding a lens infront.

With my LEX, i lose .5 stops with the adapter. and lose 1.25 stops having to zoom in to academy frame. So it's a total of about 1.75 - 2 stops with a lens attached.

The LEX is at least a stop more efficient. so we are looking at an approximate light loss ( for the original M2 glass ) of 3 stops, bringing your ISO from 320 down to 40 ASA.

You will need TONS of light to get a well exposed image. If you want a high key scene, expect to be using some serious lighting.
 
Ya, I was using the arri light calculator and was sort of coming up with the same thoughts. How many stops does CTB blue take out? Is it a 50% decrease?

How do you get around the shallow DOF problem with night interior shots, just use wide lenses all the time?

I figured my setups ISO at 80-100 with the HVX wide open and the set at 5.6 using a light meter. The new cinescreen II will help that out a bit.

What kinds of lights do you use when your shooting with a 35mm adapter. I'd like to see what other people have/rent. Are we talking 10 2k's here?
 
a CTB cuts 2 stops
So a 1 K light becomes a 250 watter. Add diffusion and it becomes a nothing light.

That's why I use hmi or fluorescent now, much more practical and saves a ton of electricity.
 
Even with a LEX, for a wide shot that's brightly lit, you will need a couple of 650watters and 1k's to get a decently lit image.

Since i'm using mostly daylight now, im using my 150 hmis and 6x55 fluorescent
 
One small correction: the HVX200A is natively about 500 ASA, The non 'A' HVX is 320 ASA.

Also, the 200A is considerably quieter with +6db of gain than the 200 is at 0. You can go to about +9 or so before you reach equivalent noise.

All of this makes the 200A *much* more adapter-friendly than the 200.
 
wow really? My hvx 200a is way noisy at +9 gain.... I cant image what the regular 200 would have been at.
 
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