What were my aims and have I achieved them?
My aims were to carry out a series of test shots to prove Inverse Square Law. I achieved these aims as I tested out this theory ten times but came to the conclusion that other factors such as lighting can affect the success of the tests. The best results were achieved outside were the light composition remained relatively the same during the photo shoot thus proving the theory.
What have I done?
I carried out a series of research led test shots to either prove or disprove inverse square law and additionally I examined the likelihood that lighting (and backdrop) plays an important part on the success or failure of a shoot when trying to prove the theory.
Test Shots for Inverse Square Law 1
See description for technical information
Test Shots for Inverse Square Law 2
Camera shake and poor lighting conditions again are a problem. I needed to experiment further to achieve my aims.
Test Shots for Inverse Square Law 3
Exposure and the Law is affected by reflections from the light coming from the doors above and the reflections in the paint work. The best image is the first which proves the law to be true.
Conclusion Part One:
I need to practice/experiment more to test out the theory. (see test shots 4, 5 etc) for inverse square law
Test Shots for Inverse Square Law 4
Test Shots for Inverse Square Law 5
Test Shots for Inverse Square Law 6
Test Shots for Inverse Square Law 7
Test Shots for Inverse Square Law 8
Test Shots for Inverse Square Law 9
Test Shots for Inverse Square Law 10
ADVANCED TECHNIQUES & PROCESSES 2A
Research into Inverse Square Law
In technical terms, inverse square law is defined as ‘’any physical law stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.’’
The law itself applies to lighting in photography which demonstrates how light works over distance and why the distance between your light source and your subject is so important.
According to the law, the power of the light will be inversely proportional to the square of the distance. So, if we take a distance of 2 and square it, we get 4, the inverse of which would be ¼ or rather, a quarter of the original power – not half.
Moving our subject 3 meters from the light (3* 3 = 9, so 1/9) the power of our light source now becomes 1/9th of what it originally was.
Moving 5ft away from the subject and correctly exposing at f/22 would therefore mean that:
The level of light is reduced to ¼ so the aperture now is f/11
Moving 10ft away from the subject and correctly exposing at f/22 would therefore mean that:
The level of light is reduced to 1/9th so the aperture now is f/5.6
Light at 2x the distance is ¼ so you would need 4x more light to compensate (2 stops)
Light at 3x the distance is 1/9 so you would need 4x more light to compensate (8x is 3 stops)
Light at 4x the distance is 1/16 so you would need 4x light to compensate (4 stops)
What have I got out of it?
My investigations at times did not uphold the inverse square law. (See photographs above). However, the changes in lighting conditions and narrow stairwells etc will have contributed to the overall proof of the theory.
The triptych and set of four reveal 5ft, 10ft on the same setting and 10ft compensated by 2 stops (as the inverse square law dictates) some appear to be true to the theory, others not. Some lighting conditions have only been reduced by stopping down to a quarter or to one and a half stops. Proving that the principles of the law apply, but they are there as a guide only and compsenatory adjustments will need to be made to take account of a loss or gain of light from other known or unknown sources.
What is next?
I have carried out ten separate experiments using a variety of locations and lighting conditions I have been able to gain experience and will implement the procedure and technical approach in my future photography.