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12/06/2005 09:50:46 AM · #1 |
I have been playing around with the inverse square law for lighting. I was wondering if anyone might have some comments on my lighting for this shot? I was trying to get the effect of the train coming out of a tunnel or around a dark turn. Comments and suggestions for improvement would be appreciated. |
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12/06/2005 11:51:06 AM · #2 |
I think the lighting looks really nice here, bit hot on the white, but nice depth of light. The thing hanging down from above kills the image for me though, would clone that out.
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12/06/2005 12:27:41 PM · #3 |
| Thanks for the comment idnic. I agree, the bar at the top must go. It is actually part of the light I was using. My main computer is broken at the moment so I have lost all my edited abilities :-) |
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12/06/2005 12:34:58 PM · #4 |
Might one ask what the inverse square law for lighting is?
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12/06/2005 12:44:54 PM · #5 |
Originally posted by Germaine:
Might one ask what the inverse square law for lighting is? |
see how many people respond at the same time ..
double the distance from the subject to the light gives you 1/4 the amount of light falling on the subject
typically based on POINT source (very small) light sources but can be generalised for all sources
Message edited by author 2005-12-06 12:45:40. |
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12/06/2005 12:45:47 PM · #6 |
The inverse square law explains the relationship between an objects distance from a light source and how much light will hit it.
I will quote it from the book I am reading "Beginner's Guide to Photographic Lighting" by Don Marr.
"...as a light source is moved farther away from its subject, it intensity drops by the square of its inverse."
The example they give in the book is say you have a light source 3ft from a subject. If you move the light source 6ft from the object, you might expect that only half as much light would be hitting the object as before since you have double the distance. What actually happens it you get less light than half, to be exact you get the inverse of the propotional difference squared. In this case, we moved 2x the starting distance so at 6 ft the object will get 1/(2)^2 the amount of light as it did at 3ft. So by doubling the distance between the light source and the object, only a quarter as much light will fall on it. |
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12/06/2005 01:06:43 PM · #7 |
I got into photography as a therapeutic means of relaxation...nobody mentioned there would be algebra involved!!!!!
Damn those high school guidance counselors...always right about "yes, you WILL use this stuff after you graduate." ;)
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12/06/2005 01:16:00 PM · #8 |
or you could just say screw the algebra and move the light around until you get what you like. ;o)
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12/06/2005 01:29:18 PM · #9 |
You really only have to remember 2 numbers to use the inverse square law; 1.4 and .7 .
If you move a light twice as far from the subject, the subject only gets .7 of the amount of light.
If you halve the light to subject distance, you get 1.4 times as much light.
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12/06/2005 01:37:28 PM · #10 |
Originally posted by Spazmo99:
You really only have to remember 2 numbers to use the inverse square law; 1.4 and .7 .
If you move a light twice as far from the subject, the subject only gets .7 of the amount of light.
If you halve the light to subject distance, you get 1.4 times as much light. |
Why, you've inverted the inverse square law! Light intensity is prortional to distance squared, not the other way around. So, doubling the distance means .25 times the light, 1/(2 squared), and halving the distance means 4x the light.
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12/06/2005 01:41:48 PM · #11 |
Originally posted by kirbic:
Why, you've inverted the inverse square law! Light intensity is prortional to distance squared, not the other way around. So, doubling the distance means .25 times the light, 1/(2 squared), and halving the distance means 4x the light. |
You are correct, Kirbic, except for the proportional part: it is inversely proportional:-) |
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12/06/2005 02:24:16 PM · #12 |
Originally posted by kirbic:
Originally posted by Spazmo99:
You really only have to remember 2 numbers to use the inverse square law; 1.4 and .7 .
If you move a light twice as far from the subject, the subject only gets .7 of the amount of light.
If you halve the light to subject distance, you get 1.4 times as much light. |
Why, you've inverted the inverse square law! Light intensity is prortional to distance squared, not the other way around. So, doubling the distance means .25 times the light, 1/(2 squared), and halving the distance means 4x the light. |
It's been a long day..........
My brain is on math overload. Sorry. Programming does that to me sometimes.
What I meant to say is that to get one stop more light, the light needs to be moved to 0.7 times the original distance.
To get one stop less, the light needs to be 1.4 times the original distance.
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12/06/2005 02:46:41 PM · #13 |
Originally posted by qbicle:
I have been playing around with the inverse square law for lighting. I was wondering if anyone might have some comments on my lighting for this shot? I was trying to get the effect of the train coming out of a tunnel or around a dark turn. Comments and suggestions for improvement would be appreciated. |
I think you have the lighting just about right in your shot. Good detail on the front of the train and a nice even fade to almost nothing farther back. Try to shoot it again without the bar and the white cloth with the gold stars on it. Maybe aim your light a little more parallel to the ground so you lessen the spotlight effect some. And possibly bring it toward the camera slightly with the idea of getting a bit more light onto the tank car. Get the angle of your light the way you want it and then you can adjust the amount of light by moving it closer or farther as desired.
Haven't read that book you quoted from yet but your description of what you were trying for reminded me of this one I shot a couple of days ago.
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12/06/2005 02:51:19 PM · #14 |
But if one train is leaving from San Francisco and the other is leaving from New York City, will it even matter what angle the light is at by the time they get to Kansas?
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12/06/2005 03:43:09 PM · #15 |
Originally posted by laurielblack:
But if one train is leaving from San Francisco and the other is leaving from New York City, will it even matter what angle the light is at by the time they get to Kansas? |
The answer is obvious, it won't matter because it will be dark when they are in Kansas.
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12/06/2005 03:51:10 PM · #16 |
Originally posted by Spazmo99:
Originally posted by laurielblack:
But if one train is leaving from San Francisco and the other is leaving from New York City, will it even matter what angle the light is at by the time they get to Kansas? |
The answer is obvious, it won't matter because it will be dark when they are in Kansas. |
Everything is dark in Kansas. They live in the dark age...well, maybe just the BOE.
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12/07/2005 01:03:33 AM · #17 |
Originally posted by Brent_Ward:
Originally posted by Spazmo99:
Originally posted by laurielblack:
But if one train is leaving from San Francisco and the other is leaving from New York City, will it even matter what angle the light is at by the time they get to Kansas? |
The answer is obvious, it won't matter because it will be dark when they are in Kansas. |
Everything is dark in Kansas. They live in the dark age...well, maybe just the BOE. |
Yeah, dark and flat.
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