Rusticle tunnel - iron formations in an old copper mine by Willy Eckerslyke

Pant y Wrach copper mine, North Wales. Natural growths in a man-made tunnel, formed over the last 150 years or so.
A nice little mine with lots to see, but access is along a rather damp adit, flooded to knee level, then a short crawl. Not somewhere to visit in your Sunday best.

Trying out some underground photo techniques. Nikon D700 with el-cheapo manual focus 28mm lens. 15sec exposures at f16 (lens is too soft at wider apertures). 1600ISO. Long exposure noise reduction ON. High ISO noise reduction OFF. Light painted with LED head torch (Black Diamond Icon). 14 images stacked and stitched in Photoshop. After struggling with modern autofocus lenses underground I decided to try something as manual as possible - an old lens with clear focus markings. It was a pleasure to use, so I'll replace it with an old Nikkor that's hopefully sharp at wider apertures.