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need some advice.

help hmi

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#1 Israel Romero Ramírez

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Posted 12 April 2016 - 01:17 PM

Hey people,

 

Currently Im working in a project for a little ad where we will make up some boys to make them old, and the maine light I would like to use is some HMI, the camera that we will be using is the FS700 with odyssey at 4k and slog  with ISO 2000

 

FS700

4k

SLOG

ISO:  2000

fps:  60 fps

 

LENS:

f=  2.8

 

SO here is what I want to ask... so I use the EXPOSEUR FORMULAS for almost everything I do even when i do phantom and they seem to work perfectly but I want to make a look like this... 

 

http://images.nation...999_600x450.jpg

 

and well this is what I will use hope I do it right!  because I can't practice before so if you guys can help me I would like to know what do you think of my setup.

 

it will be a small scene but I want to make the light come from the windows and bouncing from the inside to have a well balanced scene.  I would use a HAZE ROSCO machine and put one HMI 200W PAR from the outside and another HMI inside bouncing on the cieling so I can have both of this guys lighted well, they will always be seated and close to each other.

 

:

 

THIS IS WHAT IM TAKING WITH ME..

 

-HAZE ROSCO

-2 200W PAR LIGHT HMI

-silk and bouncing suface.

 

I want the scene to be warm, so the beam lights would look like sun beams touching the place.

 

I would ask also for a PROMIST FILTER 1/4 but i don't think we will be able to rent it, I will be also doing some other works but this is the first one and i would like if there is something i'm missing. 

 

so my calculations say that I need 24.5 fc to light this scene using a 400 ISO, so I can put the par light at 24 feet from my subjetcs, so I can have a beam of 24.6 feet.  If I use the SLOG I would be ISO 2000 as there is nothing less than that when you are using SLOG... so the calculation says that I need 4.9 fc  but I will be using an ND FILTER I think 9 nd would be nice... so I can make it to 2.8 that is what I want to use.


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#2 Satsuki Murashige

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Posted 12 April 2016 - 03:46 PM

You need 25fc to get a normal exposure. Those beams of sunlight in the photograph are probably 6 stops over normal. So you would actually need 1600fc to get the same effect.

To give you some idea of how much light you need, here's a shot I took with an F5 @ 2000 ISO, f2.8, 24fps. The light is an M18 maybe 7' outside the window on camera right. If I had wanted super hot beams like in your picture, it probably should have been at least a 4K HMI. Or a Xenon.

image.jpeg
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#3 Israel Romero Ramírez

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Posted 12 April 2016 - 04:18 PM

hey Thanks!

 

thats amazing!  grate picture!  cant wait to end this project! and share some stills.

 

so the ARRI 4000 watts hmi reflector par lite would be the one? 

 

If i take 2 poket 400w what do you think? mostly I wont be as opened as you are on your pic, there are no "full shots" mostly they are from midium shot to close up.

 

I think as the 400w hmi joker I could do it... hope hahahaha daaaaamn or at least a 800w  and another one to bounce it.

 

im using a dolly, some 24mm, 35mm, 50mm.  so this guys are old and they take some virtual reality helmets and then they enjoy the ride to the past as this helmets recreate their life when they were 19 year old.

 

so for the interiors when they are old...  I think I can be safe with 800w joker hmi at least at a distance of 40 feet to get at least F2.8... 

 

so if I use the slog and it gives me a "ISO 2000"  then I think it should be fine right?  hope I am hahahaha.

 

so if I do the formula with ISO 2000 it says that I need 4.9 FC to light it right

 

if I do it with ISO 400 I need 25 FC... and a distance of 45 feet...

 

aaaaaaaaaaaaaaaah!  damn thanks for your time Satsuki


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#4 Satsuki Murashige

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Posted 12 April 2016 - 04:38 PM

I'm a little confused. Do you want the beam of light to be very bright and overexposed like in the photograph? Or do you want the beam to light the actors to a normal exposure? Because if so, then it can't be too bright or it will overexpose the actors. If you look at my frame, the beam is probably 1.5 stops overexposed and is only edging the actor. And the beam is still very dim compared to your photograph.

I had assumed the beam of light was going to be just for the background and you were going to light your actors with the bounce in the room, plus the separate HMI in the room? Otherwise, I don't see how how you can have the beam be both very bright and also light the actors to key level.

Also, are you shooting 60fps with a shutter speed of 1/125? I think you might need more than 5fc. The F5 at least is not a true 2000 ISO, more like 800 ISO in practice. I would assume the FS7 is the same. If we take the 100 ISO + 1/48 + f2.8 = 100fc formula, then 800 ISO + 1/125 + f2.8 = 25fc. At 1/60, that would be 12fc.
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#5 Brian Drysdale

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Posted 12 April 2016 - 05:00 PM

As Satsuki says, in practise, the ISO may not be as high as you think.

 

https://www.converge...-fs7-fs700.html


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#6 Israel Romero Ramírez

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Posted 12 April 2016 - 11:56 PM

Hey again, sorry I was out of battery.

 

thanks all of you for your answers I really love this blog because you can be in contact with more people working and doing stuff.

 

Well... 

 

What I want is the HMI to be comming from the window doing sun beams to the backs of this people but I want the light to have nice and clar sun beams and I want them to be warm, .. so, wouln't a tungsten be just fine?  well thats why I want to bounse another light in to fill the characters.


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#7 Satsuki Murashige

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Posted 13 April 2016 - 12:15 AM

I'm afraid I am still confused. Do you want to backlight the actors? So the camera will face the window?

Could you maybe draw an overhead diagram of the location and where you're thinking of placing the lights, actors, and camera?
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#8 Satsuki Murashige

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Posted 13 April 2016 - 12:17 AM

Sure, if you want the light to be warm, then tungsten could be fine. It'll still have to be a pretty punchy source though.
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