In 1996 Mt Ruapehu, one of New Zealand's most active andesitic volcanoes erupted spectacularly and continuously for two days. I flew directly from Nelson by helicopter on the first day, arriving in the evening when this shot was taken of a spectacular plume of thick volcanic ash erupting from where the crater lake had been two days before. Each eruptive sequence sent out pressure waves which shook the helicopter. I love the hard line between the quite pastel blue evening sky and the tumultuous roiling waves of ash.
Taken on Nikon F.4 50mm lens. Kodachrome 64. Shutter speed 500th/sec.