On 13 September 2003 we did some night launches. We borrowed Peer's strobes, a small Neon (Argon?) strobe with a timing circuit, which drove a bigger Xenon strobe. I believe the settings mean x100 in flashes/minute. We dropped a white bottle cap for calibration at the start of each setting. The distance was about 4 m. In frames 15-19 you can see that the trigger cable to the (white) Xenon strobe must have become disconnected.

The camera was an ordinary SLR, with 800 ASA color film. We forgot to bring the big tripod and the cable release, so some frames have motion blur. The lens was a 50mm, f1.7. The location was at Gerd's house, far away from road and city lights.

The grid in the back is some kind of fencing material. 1/4" galvanized steel, 6x8" grid spacing. You can just plunk it into the ground and it will stand up.

The procedure was simple: The camera was set on 'B'; I would prepare the bottle, Gerd would open the shutter and tell me to launch, ant then close the shutter. Then we would listen for a while till we heard the bottle drop nearby, and then we would try to find it. For this we had two listener/finder assistents. Still this would sometimes take a while. The uncropped originals are at Gerd's site, then click on 'rockets' Note these cropped images are actually bigger files, they are limited to 300 pixels in this table. To see the full size, right-click on the image and select 'View Image'. These are all the frames on the film, 1-25.

Frames 1-5: Strobe at 16.4 on low setting = 27.3 Hz 67 psi, 1-liter bottle filled to bottom of tape, =xx cc.

Frames 6-14: Strobe 32.1 on low scale = 53.5 Hz

Frames 15-19: Strobe 64 on high scale = 106.7 Hz

Frames 20-25: same, 2-liter bottle 53.5 Hz

I have marked with a green arrow the location where I can see the white (masking tape) band. In most frames only one frame is caught (ignoring the bottle in the pre-launch position). Only in the last frame can you see three positions. The 1-liter bottle has greater acceleration, another reason why we didn't catch it in more flash positions.

Here is the analysis of the photographs

Even though we were at an extremely dark location, on a moonless night, there is still too much background exposure.

Next time, we'll try to improve things:

• Use this reflective tape you can get in bicycle stores, instead of just masking tape.
• Run at even higher strobe frequencies
• Rig a launch trigger, coupled with the camera release. This would involve a solenoid (from a big old relay) to pull the string or push the release lever, and Gerd's radio-controlled cable release. Then you can set the camera to 1/4 sec or so.
• Use a bigger lens. I have a f1.2, which would be 2 stops better.
• Have no bushes in the background, or use black cloth.
• Pay attention to the leveling of the camera.
• Use a heavier tripod