What sized backlight for Interview at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Photon Management

Photon Management
Shine an ever-loving light on you.


Reply
 
Thread Tools Search this Thread
Old August 24th, 2006, 09:31 PM   #1
Regular Crew
 
Join Date: Apr 2006
Location: Hammond, LA
Posts: 84
What sized backlight for Interview

I recently shot an interview, and had an Arri 650w fresnel as a key, a 300w for a fill, and a 150w for a backlight. When I exposed for the shot, I realized that the little 150w could not throw enough light on his head and shoulders to see a differnce with the 650 & 300 burning in the front. Is it a general rule to have a backlight just as powerful as my key, b/c I fell like that would have made a difference in separating him from the background.
Bryan Aycock is offline   Reply With Quote
Old August 24th, 2006, 10:51 PM   #2
Inner Circle
 
Join Date: Sep 2002
Location: San Mateo, CA
Posts: 3,840
Light falls off at the inverse square of the distance... SO

A less powerfull light (in wattage) will need to be closer to the subject in order to appear brighter.

It's possible you could have made your 150 watt back light work, IF you could have placed it in a position where it could throw enough light. ALSO where it hits your subject can make a difference. Hairlight will 'halo' the hair, shoulder light can put just a hint of edge on a dark suit, but will be lost on a lighter one. (Of course, spotting in on the light will also throw a sharper edge.) A backlight will show up better if the subject is against a dark background or 'limbo'.
Richard Alvarez is offline   Reply With Quote
Old August 24th, 2006, 11:34 PM   #3
Inner Circle
 
Join Date: Feb 2006
Location: Los Angeles, California
Posts: 2,070
And...

Richard hit the nail on the head, good advice.

Were you using hard light or a softbox on your key? An Arri 650 puts out a lot of light, I usually scrim down with at least a single when keying with it puched through a small Chimera. I typically use an Arri 650 as a key through a small Chimera, a white or gold flexfill as a fill source and an Arri 150 fresnel as a hairlight or rimlight. Sounds to me like your ratios were off which would make sense. Unless you needed a super wide framing, the Arri 300 sounds like overkill as a fill light, I would have reversed and used the 150 as a fill and the 300 as hairlight.

But I do succesfully use the Arri 150 fresnel on a dimmer as my typical hair/rim light when keying with the Arri 650 fresnel.

You should set up the old camera and monitor and shoot tests and you will soon discover the correct lighting ratios.

Best,

Dan
Dan Brockett is offline   Reply With Quote
Old August 26th, 2006, 11:23 PM   #4
Regular Crew
 
Join Date: Aug 2006
Location: Boston, MA
Posts: 34
According to Doug Jensen's excellent how to DVD on interview lighting, a 250 watt Lowell Pro light, barndoored, does the trick. His Vortex Media should be a sponsor here. He delivers a nicely distilled mini-workshop just on lighting interviews that I found helpful. Recommends a kit costing less than 1500.00-- and itemizes it line by line, dollar by dollar.

www.vortexmedia.com

I own no stock in Vortex Media. (But i wish I did.)

- Loren
Loren Miller is offline   Reply With Quote
Old August 26th, 2006, 11:36 PM   #5
Regular Crew
 
Join Date: Jul 2005
Location: Perth WA Australia
Posts: 124
Get someone with a large flecki to bounce the light and fill in the gaps.Cut down on the wattage,nothing looks more phony than a blown out interveiw scene.
Joe Barker is offline   Reply With Quote
Old September 12th, 2006, 10:37 AM   #6
Regular Crew
 
Join Date: Sep 2006
Location: San Francisco California
Posts: 52
Blown Away

I have a rifa-lite 66 (750w). Would this be too powerful and "blow away" my interview subjects? I plan toplace it farther back and somewhat off to the side for my interviews.
Sal C. Martin is offline   Reply With Quote
Old September 12th, 2006, 12:03 PM   #7
Inner Circle
 
Join Date: Sep 2003
Location: Portland, Oregon
Posts: 3,259
Quote:
Originally Posted by Sal C. Martin
I have a rifa-lite 66 (750w). Would this be too powerful and "blow away" my interview subjects? I plan toplace it farther back and somewhat off to the side for my interviews.
Sal, test it out.

I think the rifa-66 is a very nice light, and capable of supporting a two-person interview. You'd need to get it far enough away to light two people evenly.

The rifa series are very efficient, so, yes, a 750 puts out a lot of light.

Be aware that if in your tests you find you're working the rifa so far away that it's inconvenient, or you're starting to lose the "wrapping" effect of the soft box, you can lamp it with a 500w bulb. http://lowel.com/rifa/rifa66_b.html#info
Seth Bloombaum is offline   Reply With Quote
Old September 12th, 2006, 01:31 PM   #8
Inner Circle
 
Join Date: Jun 2003
Location: Toronto, Canada
Posts: 4,750
You could also place diffusion on the light (i.e. use clothespins to hold the gel) to knock down the intensity... in case you usually want the 750W bulb in there. In this case, you just use the diffusion to do the same thing a neutral density gel would do.
Glenn Chan is offline   Reply With Quote
Old September 12th, 2006, 10:06 PM   #9
New Boot
 
Join Date: Jul 2006
Location: Costa Mesa, CA
Posts: 18
Quote:
Originally Posted by Sal C. Martin
I have a rifa-lite 66 (750w). Would this be too powerful and "blow away" my interview subjects?
"blow away" is usually a function of bad exposure and not getting the ratios of key-fill-back-background levels right.

Using a 750w, even in a Rifa, is a lot of light. I'm always in a bid to save power and heat so I try not to use anything over 500w. But if you do a lot of diffusion in front of the lights (like the movie crews that start with a 10K and reduce it to 25fc with layers of silks) then more wattage is required.

As for backlights, I'm using that small 250w Rifa on a dimmer and I find that works great. Sometimes I just bounce a 100w into an art card for a back. You find that just like the key light, a softer back light can make a world of difference. If you've ever had a female subject with "the frizzies" a hard back light can drive you mad. A soft back light reduces that problem to almost unnoticeable while still getting a great hair light with separation.

t
Tom Tanquary is offline   Reply With Quote
Old September 13th, 2006, 06:46 PM   #10
DVCreators.Net
 
Join Date: Oct 2001
Location: Seattle, WA
Posts: 888
Toss an Egg Crate on that Rifa 750 and you'll cut the output of the light and have more control of where the light is going.
__________________
Guy Cochran
DVinfo Sponsor, Cool Gear - DVeStore!
Guy Cochran is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > Photon Management

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 06:47 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network