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Author Topic: Why are there multiple shadows on a football field?  (Read 9691 times)

Offline chris

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I was asked by someone recently why players on the field at an illuminated stadium produce multiple shadows. Specifically the asker said that players made 4 shadows - so why four? (I presume there were four banks of lights at each corner of the stadium).

Chris


 

Offline LeeE

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Why are there multiple shadows on a football field?
« Reply #1 on: 13/02/2009 21:26:52 »
Yup - you've answered it.  If you think about how shadows are formed it's obvious; you can't have a shadow without a corresponding source of light, whether it be direct or reflected.
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #2 on: 13/02/2009 22:47:39 »
What would happen if there were lights around the entire stadium? Would you see any shadows then?
 

Offline DrN

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Why are there multiple shadows on a football field?
« Reply #3 on: 13/02/2009 22:48:59 »
I suppose you'd see a homogenous circle of shadow around each player!
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #4 on: 13/02/2009 22:52:37 »
But won't the lights cancel each other out?
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #5 on: 13/02/2009 23:36:01 »
I would think that would be the case also.....I would think by creating a series of lights placed evenly around the Field that they would in essence essence light the whole field more less like light day time and cancel out the multiple shadows by making it a brighter more even light that is not in such a defined angle and trajectory...patternlike surround sound only wit light and not sound!
 

Offline DrN

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Why are there multiple shadows on a football field?
« Reply #6 on: 14/02/2009 00:20:52 »
I'm not sure - surely the bits that would normally be in shadow will still get less light than the bits not in shadow? Am I making sense?

Light from one side will hit the person and cause a shadow, while light from the opposite side will shine onto this shadow (and cause a shadow on the other side). However, the shadow area will have less total light shining on it than the surrounding area that is not in the shadow.

Even in the case of 4 lights you still see 4 shadows. The lights opposite each other do not appear to cancel each other out, they just make the shadows fainter.
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #7 on: 14/02/2009 00:31:04 »
I suppose in an oval stadium, some lights will be closer to the person and some will be further away. Not to mention that the person will be moving around constantly. So if it was a round circular stadium and the person stood right in the middle will there be shadows? :)
« Last Edit: 14/02/2009 00:32:48 by Chemistry4me »
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #8 on: 14/02/2009 01:31:37 »
HMMMMMM Someone should get a medium size box.. clamp 4 mini mag lights to the 4 corners of the box... line bottom with green felt to simulate football field then add a toy soldier or Pond from a chest game for a person.. check the shadows and then add multiple lights around the edge of the box shining in like stadium lights and see what happens with the shadows...as you add equal lighting all around the box..
This should be done in a dark room eh? Do you think it would work.. given one has enough mini mag lights eh?

Neil.. Want to do some empirical study...?
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #9 on: 14/02/2009 01:34:27 »
Neil.. Want to do some empirical study...?
Go to your neighbours house and 'borrow' some lightbulbs?
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #10 on: 14/02/2009 01:37:57 »
I have tons of light bulbs but I think they will be far too bright for the scale of the model.. don't you?

Your neighbors are probably used to you doing that eh?
 

Offline JnA

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Why are there multiple shadows on a football field?
« Reply #11 on: 14/02/2009 02:07:14 »
when you light someone on stage you use counter lights to cut shadows, so you'd think that the four opposing lights would cancel out shadows.. 
however, theatre lights are able to be focused to created a hot spot, so final defining lines are easier to cancel out (each light regardless of distance to the player will be focused at the appropriate level). Stadium lights cast a full beam.. therefore the lights that are nearer the player will cast a stronger shadow line, the ones on the other side will cast a softer one.. since they are not focused to the same strength. (It would be near impossible to have shadowless soccer players (I assume when you say 'football' you mean Soccer, unless you include many more lights and have constant adjustments according to play.. actually that'd be quite a challenge and pretty expensive.)
« Last Edit: 14/02/2009 02:11:19 by JnA »
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #12 on: 14/02/2009 05:19:34 »
But I was talking about the entire stadium being surrounded by lights. Not just a couple of stands...
 

Offline RD

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Why are there multiple shadows on a football field?
« Reply #13 on: 14/02/2009 22:05:55 »
If you need light which surrounds the subject then try one of these ring flashes ...



http://www.photolearn.co.uk/free_pdf/ringflash.pdf

Ring flashes are flashguns where the flash tube is a ring around the lens,
they are said to provide very uniform "shadowless" illumination: (e.g. minimizes wrinkles).


http://en.wikipedia.org/wiki/Ring_flash

« Last Edit: 14/02/2009 22:08:25 by RD »
 

Offline DrN

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Why are there multiple shadows on a football field?
« Reply #14 on: 14/02/2009 22:16:14 »
It would need to be pretty big to surround an entire football stadium!
 

Offline RD

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Why are there multiple shadows on a football field?
« Reply #15 on: 14/02/2009 22:31:38 »
The suggestion was to use toy soldiers (Subbuteo ?)
 

Offline DrN

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Why are there multiple shadows on a football field?
« Reply #16 on: 14/02/2009 22:37:44 »
Ah yes. Do you have both? The light-ring and a sabbuteo set? I'm afraid I have neither!
 

Offline LeeE

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Why are there multiple shadows on a football field?
« Reply #17 on: 14/02/2009 23:52:39 »
Ring-flashes are usually only used in surgical or macro/micro photography.  For most other areas you actually want some degree of shadow, with bounced flash being most commonly used.
 

Offline Chemistry4me

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Why are there multiple shadows on a football field?
« Reply #18 on: 15/02/2009 03:21:16 »
Circular fluorescent lightbulbs? Won't they work?
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #19 on: 15/02/2009 04:57:06 »
Cool figures RD... Some good ideas people...
 

Offline Bored chemist

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Why are there multiple shadows on a football field?
« Reply #20 on: 15/02/2009 13:23:07 »
I suppose in an oval stadium, some lights will be closer to the person and some will be further away. Not to mention that the person will be moving around constantly. So if it was a round circular stadium and the person stood right in the middle will there be shadows? :)
Yes.
You can see the person so they are clearly reflecting light. If they were not there that light would reach the ground. Wher it doesn't reach the ground because it is being reflected (or absorbed for that matter) by the person, there is a shadow.
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #21 on: 15/02/2009 13:58:56 »
I understand that thr light reflects off th body casting the shadow.

How does the body absorb the light..is that not different?
 

Offline Bored chemist

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Why are there multiple shadows on a football field?
« Reply #22 on: 15/02/2009 19:41:29 »
I understand that thr light reflects off th body casting the shadow.

How does the body absorb the light..is that not different?
No, the body gets in the way of the light and so it casts a shadow.
It does that whether the light is reflected or absorbed.
 

Offline Karen W.

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Why are there multiple shadows on a football field?
« Reply #23 on: 16/02/2009 00:18:19 »
I suppose in an oval stadium, some lights will be closer to the person and some will be further away. Not to mention that the person will be moving around constantly. So if it was a round circular stadium and the person stood right in the middle will there be shadows? :)
Yes.
You can see the person so they are clearly reflecting light. If they were not there that light would reach the ground. Wher it doesn't reach the ground because it is being reflected (or absorbed for that matter) by the person, there is a shadow.

I understand about the reflection of Light off from the body... but as you said above,

 "where it does't reach the ground because it is being reflected ( or aborbed for that matter) by the "person," there is a shadow."

I just did not understand how light could be absorbed by a body or solid object....blocked or reflected..I get....??? see what I mean? or not? I'm confused too! Lol..
 

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Why are there multiple shadows on a football field?
« Reply #23 on: 16/02/2009 00:18:19 »

 

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