Soft light and distance - Page 2 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 September 15th, 2007, 04:50 PM   #16
Wrangler
 
Join Date: Jan 2002
Location: Los Angeles, CA
Posts: 6,781
Back to the original question for a second. Imagine you are shooting a product shot of a golf ball on a tee, a few inches away from a background surface. Let's also imagine you have a 12" square Chimera (flo, whatever--doesn't matter what the source, it's 12 x 12 of evenly distributed light).

Position the light 10 feet away and fire it up. We would expect the golf ball to throw a fairly defined shadow onto the background. Now move it to within six inches of the golf ball (and knock the output down so that it exactly matches the level from 10 feet away). The shadow will be all but nonexistent.

The issue of output level is somewhat irrevelant to the discussion, as it is entirely possible with even humble lighting sources to significantly alter the quality (hard to soft etc) of a given source depending on where you place it relative to the subject. The example above is extreme of course, but even if that same source was placed at a more realistic six feet away versus 2 feet away, there would still be a noticeable difference in the quality of light/shadow and the exposure difference could easily be contained by stopping down the camera and/or applying scrim/nets/dimmer etc to the unit.
__________________
Charles Papert
www.charlespapert.com
Charles Papert is offline   Reply With Quote
Old September 17th, 2007, 03:12 PM   #17
Major Player
 
Join Date: Aug 2006
Location: Columbus, Ohio
Posts: 423
Thank you Charles.

That was my point in mentioning the sun earlier. If you're 2 inches away from the sun (and figure out a way to not melt/burn) there would be virtually no shadows because of the immense size of the sun compared to you. Now here on terra firma, because of the distance of the sun and the relative size of the sun because of that distance the sun becomes a "hard" light source. It's all relational - between the object and the light.

Another example would be if you took a standard softbox (pick your favorite brand and shape) and move an object close to it, the light will have soft characteristics.

Now let's move the same object a substantial distance from the light (let's be absurd - let's talk miles, not feet). At this distance, the light (if we had a camera sensitive enough to pick up the light and everything else is dark) will have hard characteristics.

This is because at this absurd distance all of the light that is reaching the object is traveling in near parallel. And the near parallel light will cast hard, or sharp, or distinct shadows. The reason for the soft shadows in the first part of the example is that the light is striking the object from many different angles.
__________________
"... the drama is on your doorstep..." - John Grierson
www.grvideo.net
Kevin Randolph is offline   Reply With Quote
Old September 17th, 2007, 03:18 PM   #18
Wrangler
 
Join Date: Jan 2002
Location: Los Angeles, CA
Posts: 6,781
Yes, we are saying the same thing. I just thought that it would be helpful to include an example that could possibly be duplicated here on earth (since few of us have access to super-insulated spaceships etc, although I would not be surprised if Jim Jannard had something along these lines).
__________________
Charles Papert
www.charlespapert.com
Charles Papert is offline   Reply With Quote
Old September 18th, 2007, 10:14 AM   #19
Regular Crew
 
Join Date: Feb 2005
Location: Dallas, TX
Posts: 108
On a more practical level...

You'll likely find softboxes almost useless for anything other than static product shots, faces, etc. a 6' x 6' Butterfly, backlit with a sheer fabric, can generally be good for full-frame people shots. If you want to move around a room, you need a BIG soft source; bounce off an entire white wall or scrim up a wall of bedsheet-size fabric on stands with several open face lights behind them (work lights can do this well, but the rectangular open faced lights with barndoors are better -- and there are usually several on eBay any given week). In this case, you need enough room to get your lights a few feet back from the scrims, and aim them towards the top for a more natural look. Bouncing off the ceiling at the same time can add to the natural factor. You'll get to the point that when you look at a given set, you'll know what you need to get the look you want. All the pricey gear in the world can't beat experience.
Michael Carter is offline   Reply With Quote
Old September 18th, 2007, 11:10 PM   #20
Trustee
 
Join Date: Nov 2005
Location: Honolulu, HI
Posts: 1,961
How far would I need to be away from a neutron star to get a hard light source?

Are black holes good negative fill or does the Hawking radiation negate the black?

Seriously, I would explain a "soft" source as simply one relatively large compared to the subject. Think of every tiny point of a light source as an individual ray of light that casts it's own shadow. Draw an imaginary line between all points of a light source and the subject and you will realize that a large source will make infinite shadows in all directions from the features of a subject. All those little shadows in random directions blur the line of the shadow. A hard light like a tungsten filament inside a clear glass bulb will make a very distinct shadow. It is possible to make a soft source of light from tungsten filaments by having lots and lots of them spread out over a few feet. Get a bundle of rope light and put it near a subject. All those points of light spread out the shadows.
Marcus Marchesseault is offline   Reply With Quote
Old September 19th, 2007, 05:21 PM   #21
Major Player
 
Join Date: Aug 2006
Location: Columbus, Ohio
Posts: 423
Cute... .
__________________
"... the drama is on your doorstep..." - John Grierson
www.grvideo.net
Kevin Randolph is offline   Reply With Quote
Old September 19th, 2007, 10:49 PM   #22
Trustee
 
Join Date: Nov 2005
Location: Honolulu, HI
Posts: 1,961
I actually agree that using the sun is a good point. It illustrates that relative size and distance are important to how soft a light source appears. I visualize soft sources as individual points of light all generating their own shadow to make it simpler to comprehend.
Marcus Marchesseault is offline   Reply With Quote
Old September 20th, 2007, 06:37 AM   #23
Major Player
 
Join Date: Dec 2005
Posts: 848
If a source is to maintain the same character of light & shadow as it is moved away from the subject the ratio of the diameter to distance must remain constant. As the ratio decreases the light becomes harder.

I wouldn't get too hung up on theoretical concepts about point sources; an approximation is good enough for understanding. The idea of a source consisting of a bunch of point sources originating from various points does a good job of conveying how the character of light is affected by their distribution.
Jim Michael 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 05:07 PM.


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