George Wallace said:
Shooting tanks is actually a lot like shooting fireworks, the LAV's are even easier.
Step 1. Forget about doing it handheld. This is absolutely essential. With the shutter speed drag you are going to have to work at a tripod/beanbag/6 foot table is 100% required no if ands or buts. I can not stress this enough. Forget about handholding. Put it out of your mind. No joke.
Step 2. Use a cable release or a self timer. For these night shots I actually used a timer controller cable release, found the right combination of aperture, shutter speed and ISO and set it up to take a 15 second exposure 15 times. The camera just does the rest.
Step 3. A great place to start is f/2.8-ish and 30 second exposures. A wide aperture will let you catch things like the sabot shoe ripping off as it lets more light through to the sensor. Things like explosions tend to be burning fast and short and if you use something more narrow not enough light will reach it to register. I manually focus on the APC, with wide angle lens just prefocus on infinity.
Step 4. Shoot lots.
For a tank that has a lot more platform rock I would set the camera to bulb (as in the shutter stays open as long as the shutter release is held down). Hold the shutter open with the cable release and then flinch release it when the tank fires. Late at night it shouldn't overexpose and if it does you can just lower the ISO, which has the side benefit of reducing the noise in the image as well. If you release right as its firing you should get a decent view of the tracer ripping out but it should close fast enough the tank won't "ghost" in the frame. I would also setup as far away as possible and use a longer telephoto lens. This will flatten out the image and avoid problems with the blast rocking the camera. Just how I would do it, open to suggestions.
I forgot to mention, if there isn't enough ambient light to illuminate the tank or whatever vehicle is firing, I'd set a second curtain flash at maybe a stop or two under what the meter reads.
