[i speak in math]

Here's a recent one:

From Strobist

Nov 11, 2009
Model: PENTAX K20D
ISO: 400
Exposure: 10.0 sec
Aperture: f/5.6
Focal Length: 50mm
Flash Used: No
Strobist info: lp120 at 1/2 power from camera left (15') triggered with cactus v4

On a side note, this shot was a little tricky, technically.

I needed a 10 sec exposure to get the candle light where I wanted it. But that would have left the soldier marching by nearly pitch black and completely blurred. I tried a played around with the flash and found 1/2 power looked about right. When the next soldier walked by, I blinded him using the test flash mid shot.

Problem? Yes. The candles had burned into the frame (10 sec exposure, remember?). When I flashed the soldier, it left his image superimposed over the luminaries. This made him look transparent and ghost-like.

I had to catch the soldier in between the luminaries so that none of them shown through him.

I hooked up my cactus triggers instead of using the test flash button myself. I used my voice activated boom to hold the flash and looked through the viewfinder. When the soldier got to the perfect spot, I hit the shutter.