I shoot my beam shots on manual, and when I started I tried to get a setting on the camera that accurately reflected what the beam seemed to look like to me in real life. That meant that with things like a Cateye light that runs off AA cells, the beamshot looks like a dim little splash of grey in a black field.

I use the same settings when shooting other lights once I locked in on it. When I switch cameras I might have to adjust a bit, but if the ISO setting is the same it should be pretty close.

6 seconds is ridiculous. That's nothing like an accurate representation. I think I go with something around 1/2 or 1 second. It's been a while since I did beam shots, and I always just pull up an older one and check to see what settings I used then.