adjustable shutter speed is a must for good beam shots. I wonder about ISO. I heard 200 is good for light painting, I reasoned capturing beams is a similar endeavor, so I use that. it seems to work but I'm open to suggestion.
but yeah when I take beam shots, the exposure length I use changes depending on factors like angle, fog, and laser power. I'd agree around 1 sec should be good for this 589. the smaller the incriment by which the shutter speed can be adjusted, the better. usually I take a sequence of progressively longer exposures and then pick a favorite. my camera's screen does not properly display some wavelengths, even though the camera does pick them up, I have to judge them by how they look on a computer screen