Practical 1.2 - Position / Distance

So, for this Tutorial, the end result was that we should be able to understand the following statements:-

1. Light has depth of field.
2. With enough light, you can turn a white wall black.

I have to say I'm pretty excited about this one, since I have always wondered how photographers manage to make a light background appear almost Black. I have done it myself on a couple of rare occasions, but only by pure chance. I'm really looking forward to being able to controll the effect at any given time.

The principle is based on something called "The inverse Square Law", which is something I vaguely recall from my School days in the Physics classroom. As David says, the laymans explaination is as follows:

"The closer you are to the light source, the more powerful the light. Get real close and it gets really powerful. Get far away, and it gets weaker."

Also,

"The closer you get to the light source, the quicker the lighting values change as you move in. When you get farther away, small differences in distance (from the light) become meaningless."

Well, that seems to make sense to me, but I must still admit, that the idea that this concept can actually make the background go "Black", still seems like a tall order to me.

So on to the testing. (Back in an Hour or so)

.......ok im back.

Wow! I'm really excited and impressed by the results from this. I cant wait to get my kids round at the weekent to play with this some more!

Here is a composite I made up with the setup's and resulting Images:



Top Image:
Flash 1/4 Power - 50mm Zoom
Distance - 3 Meters
1/200 f7.1 iso200

Center Image:
Flash 1/16 Power - 50mm Zoom
Distance 1.5 Meters
1/200 f7.1 iso200

Bottom Image:
Flash 1/64 Power - 50mm Zoom
Distance 12 Inches
1/200 f11 iso200

I'm finding this really interesting, and I feel like a whole world of possibilities has just opened up for me. I would never have dreamed of getting a Flash within a foot of a subjects face, I just always assumed it would have destroyed the Image. Oh how my kids will love me this weekend. Mwahahahahaa!

Original Tutorial - Lighting 102: 1.2 - Position Distance